Russian President Vladimir Putin has warned that Ukrainian statehood is in jeopardy - and likened the West's sanctions on Russia to "declaring war" – while a promised ceasefire in the port city of Mariupol collapsed amid scenes of terror. 

With the Kremlin's rhetoric growing fiercer and a reprieve from fighting dissolving, Russian troops continued to shell encircled cities and the number of Ukrainians forced from their country grew to 1.4 million. 

Bereft mothers mourned slain children, wounded soldiers were fitted with tourniquets and doctors worked by the light of their cellphones as bleakness and desperation pervaded. 

Putin continued to pin the blame for all of it squarely on the Ukrainian leadership and slammed their resistance to the invasion. 

Ukrainian soldiers drive on an armoured military vehicle in the outskirts of Kyiv. Photo / AP 

"If they continue to do what they are doing, they are calling into question the future of Ukrainian statehood," he said. 

"And if this happens, it will be entirely on their conscience." 

He also hit out at Western sanctions that have crippled Russia's economy and sent the value of its currency tumbling. 

"These sanctions that are being imposed, they are akin to declaring war," he said during a televised meeting with flight attendants from Russian airline Aeroflot. 

"But thank God, we haven't got there yet." 

Zelenskyy's 'desperate' plea to US Congress: Send more planes 

Fighting for his country's survival, Ukraine's leader made a "desperate" plea Saturday to American lawmakers for the United States to help get more warplanes to his military and cut off Russian oil imports as Kyiv tries to stave off the Russian invasion. 

President Volodymyr Zelenskyy opened the private video call with U.S. lawmakers by telling them this may be the last time they see him alive. He has remained in Kyiv, the capital, which has a vast Russian armored column threatening from the north. 

Appearing in what is now his trademark army-green shirt in front of a white wall with the Ukrainian flag, he told them Ukraine needs to secure its skies, either through a no-fly zone enforced by NATO or through the provision of more warplanes so Ukraine could better defend itself. Zelenskyy has been pleading for a no-fly zone for days, but Nato has refused, saying it could provoke a widespread war with Russia. 

The hourlong exchange with some 300 members of Congress and their staffs came as Russian troops continued to shell encircled cities and the number of Ukrainians who have fled the country grew to 1.4 million. 

"President Zelenskyy made a desperate plea," said Senate Majority Leader Chuck Schumer. 

He said Zelenskyy wants the U.S. to facilitate the transfer of planes from Eastern European allies. "I will do all I can to help the administration to facilitate their transfer," Schumer said. 

The U.S. is considering sending American-made F-16s as backfill to former Soviet bloc countries in Eastern Europe that are now members of NATO. They, in turn, would send Ukraine their own Soviet-era MiGs, which Ukrainian pilots are trained to fly. 

There appears to be a logistical problem, however, in sending the F-16s to Poland or other East European allies because of a production backlog. These countries would essentially have to give their MiGs to the Ukrainians and accept an IOU from the U.S. for the F-16s. The situation is further complicated because the next shipment of F-16s is set for Taiwan, and Congress would be reluctant to delay those deliveries as it eyes China. 

Secretary of State Antony Blinken indicated the fighter jets are under consideration after meeting with Ukrainian Foreign Minister Dymtro Kuleba at the Poland-Ukraine border outside the town of Korczowa. 

"We are talking about and working on everything," Blinken told reporters. 

Blinken reiterated that the U.S. support for Ukraine "not only has been unprecedented, not only is it going to continue, it's going to increase." 

The U.S. Congress is working on a $10 billion package of military and humanitarian aid to Ukraine. Schumer told Zelenskyy lawmakers hope to send it quickly to Ukraine, according to a person on the call and granted anonymity to discuss it. 

When Senate Republican leader Mitch McConnell asked about the types of military support his country needs, Zelenskyy said drones as well as planes would be the most helpful. 

During the call, Democratic Sen. Joe Manchin of West Virginia asked Zelenskyy about the idea of banning the import of Russian oil to the U.S., according to two other people granted anonymity to discuss the private call. They said Zelenskyy indicated such a ban would be effective in putting pressure on Russia. 

Republicans and a growing number of Democrats, including Speaker Nancy Pelosi, back the idea of an Russian oil import ban. The Biden administration has so far resisted that step, worried about rising prices at the pump. 

Zelenskyy urged US lawmakers to sanction Russia's oil and gas sector, which has so far escaped the mounting sanctions imposed by the Biden administration and other countries. He also urged lawmakers to suspend Visa and Mastercard credit card access in Russia. 

"Anything that could hurt the Russian economy will help the Ukrainian people and may make this war more difficult for Putin," Sen. Lindsey Graham, R-S.C., said in a video posted to Twitter after the call. 

Zelenskyy's office said he also suggested the U.S. consider imposing an embargo on all Russian goods and stripping Russia of its most-favored-nation trade status. 

Lawmakers are concerned that Zelenskyy will be killed in the Russian invasion. They are also worried that a Ukrainian government under assault will be unable to function and to receive aid. 

When one lawmaker asked diplomatically what would happen if he was killed, Zelenskyy acknowledged the concerns but implored Congress to do whatever it can to help Ukraine fight off Russia's assault on his country. 

Sen. Ben Sasse, R-Neb., said in a statement that Zelenskyy's "message is simple: 'close the skies or give us planes.'" 

Mastercard and Visa latest to suspend operations in Russia 

Mastercard and Visa have announced they have suspended all operations in Russia, the latest in a series of companies stopping their business in the country, following the invasion of Ukraine. 

Ukraine says more than 10,000 Russians killed 

Ukrainian Foreign Minister Dmytro Kuleba on Saturday echoed the president's assertion that Russia has lost more than 10,000 troops. 

Kuleba also said in a video message released by the Ukrainian government that the Russians had lost dozens of aircraft and hundreds of armored vehicles. 

The claim could not be independently verified. The Russian military doesn't offer regular updates on their casualties. On Wednesday, military officials revealed a death toll of 498. 

"Russians keep bearing devastating losses on the ground, and I cannot understand how mothers, wives and daughters of these Russian soldiers bear this pain, seeing how President Putin sends more and more of their beloved ones to Ukraine," Kuleba said. 

Kuleba added, "Ukraine is bleeding but Ukraine has not fallen and stands (with) both feet on the ground." 

Ceasefire fails, Russian troops intensify shelling 

Russian forces have intensified shelling in the port city of Mariupol, including with the use of airplanes, the mayor said Saturday night. 

"The city is in a very, very difficult state of siege," Vadym Boychenko told Ukrainian TV. "Relentless shelling of residential blocks is ongoing, airplanes have been dropping bombs on residential areas." 

Boychenko said that thousands of children, women and the elderly came under fire as they arrived in the morning for a possible evacuation through a safe passage corridor. Russia promised to stop the shelling of Mariupol, a port city of 430,000, and Volnovakha, a city in the east, but violated the cease-fire. 

Russia has made significant advances in the south, clearly seeking to cut off Ukraine's access to the sea. Capturing Mariupol, which has been fending off the attack for six days, could allow Russia to build a land corridor to Crimea, which it annexed in 2014. 

Earlier updates continue below: 

Ten days after Russian forces invaded, the struggle to enforce the temporary ceasefire in Mariupol and the eastern city of Volnovakha showed the fragility of efforts to stop the fighting across Ukraine. 

Ukrainian officials said Russian artillery fire and airstrikes had prevented residents from leaving before the agreed-to evacuations got under way. 

The third round of talks since Russia invaded will take place on Monday, Davyd Arakhamia, a member of the Ukrainian delegation, said last night. He didn't give further details, including where they will take place. The last round was held in Belarus. 

Previous meetings were held in Belarus and led to the failed ceasefire agreement to create humanitarian corridors for the evacuation of children, women and older people from besieged cities, where pharmacies have run bare, hundreds of thousands face food and water shortages, and the injured have been succumbing to their wounds. 

In comments carried on Ukrainian television, Mariupol Mayor Vadym Boychenko said thousands of residents had gathered for safe passage out of the city when shelling began Saturday. 

"We value the life of every inhabitant of Mariupol and we cannot risk it, so we stopped the evacuation," he said. 

People lie on the floor of a hospital during shelling by Russian forces in Mariupol. Photo / AP 

The West has broadly backed Ukraine, offering aid and weapons and slapping Russia with vast sanctions. But the fight itself has been left to Ukrainians, who have expressed a mixture of courageous resolve and despondency. 

Russian troops advanced Saturday on a third nuclear power plant, having already taken control of two of the four operating in the country. 

Ukrainian President Volodymyr Zelenskyy pleaded with American lawmakers for additional help even as he insisted the enemy was being defeated. 

"We're inflicting losses on the occupants they could not see in their worst nightmare," the Ukrainian leader said. 

Russian troops took control of the southern port city of Kherson this week. Although they have encircled Kharkiv, Mykolaiv, Chernihiv and Sumy, Ukrainian forces have managed to keep control of key cities in central and southeastern Ukraine, Zelenskyy said Saturday. 

Earlier, the Russian defence ministry said it had agreed with Ukraine on evacuation routes out of the two cities. 

Before the announcement, Russia's assault had caused growing misery in Mariupol, where journalists witnessed doctors make unsuccessful attempts to save the lives of wounded children, pharmacies ran out of crucial medicine and hundreds of thousands of people faced food and water shortages in freezing weather. 

In recent days, Ukraine had urged Moscow to create humanitarian corridors to allow children, women and older adults to flee the fighting, calling them "question No. 1". 

Zelenskyy held out the possibility that talks with Russia could result in a sustained, if limited ceasefire. 

Elsewhere in the country, Ukrainian forces were holding key cities in central and southeastern Ukraine, while the Russians were trying to keep Kharkiv, Mykolaiv, Chernihiv and Sumy encircled, he said. 

Russian Foreign Minister Sergey Lavrov said Russia was ready for a third round of talks on that and other issues, but he asserted that "the Ukrainian side, the most interested side here, it would seem, is constantly making up various pretexts to delay the beginning of another meeting." 

A woman holds a dog while crossing the Irpin River on an improvised path under a bridge that was destroyed by a Russian airstrike. Photo / AP 

Diplomatic efforts continued as US Secretary of State Antony Blinken arrived in Poland to meet with the country's prime minister and foreign minister, a day after attending a Nato meeting in Brussels in which the alliance pledged to step up support for eastern flank members. 

In Moscow, Israeli Prime Minister Naftali Bennett was meeting with Putin at the Kremlin. 

Israel maintains good relations with both Russia and Ukraine, and Bennett has offered to act as an intermediary in the conflict. No details of the meeting have yet emerged. 

In the wake of Western sanctions, Aeroflot, Russia's flagship state-owned airline, announced that it plans to halt all international flights. except to Belarus, starting Tuesday. 

At least 351 civilians have been confirmed killed since the invasion began on February 24, but the true number is probably much higher, the UN human rights office has said. 

Zelenskyy said yesterday that 10,000 Russian troops had died in the war, a claim that could not be independently verified. 

"We're inflicting losses on the occupants they could not see in their worst nightmare," the Ukrainian leader said. 

The Russian military, which doesn't offer regular updates on casualties, said Wednesday that 498 of its troops had been killed. 

Ukraine's military might is vastly outmatched by Russia's, but its military and volunteer forces have fought back with fierce tenacity since the invasion. 

Even in cities that have fallen to the Russians, there were signs of resistance. 

Onlookers in Chernihiv cheered as they watched a Russian military plane fall from the sky and crash, according to video released by the Ukrainian government. 

In Kherson, hundreds of people protested the invasion, shouting, "Go home." 

A vast Russian armoured column threatening Ukraine's capital remained stalled outside Kyiv. 

Ukrainians crowd under a destroyed bridge as they try to flee crossing the Irpin river in the outskirts of Kyiv. Photo / AP 

Ukrainian presidential adviser Oleksiy Arestovich said the military situation was quieter overall yesterday and Russian forces "have not taken active actions since the morning." 

While the shelling in Mariupol showed Russia's determination to cut Ukraine off from access to the Black Sea and the Sea of Azov, further damaging the country's economy, it was Putin who was most on the offensive with his comments warning that a no-fly zone would be considered a hostile act. 

Nato has said it has no plans to implement such a no-fly zone, which would bar all unauthorised aircraft from flying over Ukraine. Western officials have said the main reason is a desire to not widen the war beyond Ukraine. 

Zelenskyy has pleaded for a no-fly zone and lashed out at Nato for refusing to impose one, warning that "all the people who die from this day forward will also die because of you". 

As the United States and other Nato members send weapons for Kyiv, the conflict is already drawing in countries far beyond Ukraine's borders. 

As Russia cracks down on independent media reporting on the war, more major international news outlets said they were pausing their work there. 

Putin said nothing warrants imposing martial law at this point. 

And in a warning of a hunger crisis yet to come, the UN World Food Programme has said millions of people inside Ukraine, a major global wheat supplier, will need food aid "immediately". 

Ukraine's president was set to brief US senators by video conference as Congress considers a request for $10 billion in emergency funding for humanitarian aid and security needs. 

The UN Security Council scheduled an open meeting for Monday on the worsening humanitarian situation. 

The United Nations estimates that 12 million people in Ukraine and four million fleeing to neighbouring countries in the coming months will need humanitarian aid. 

Kyiv's central train station remained crowded with people desperate to flee. 

"People just want to live," one woman, Ksenia, said.