The bodies of more than 900 civilians have been discovered in the region surrounding the Ukrainian capital after Russia's withdrawal — most of them fatally shot, police said on Friday, an indication that many people were "simply executed". 

The jarring number emerged shortly after Russia's Defence Ministry promised to step up missile attacks on Kyiv in response to Ukraine's alleged aggression on Russian territory. That ominous warning followed the stunning loss of Moscow's flagship in the Black Sea, which a senior US defence official said on Friday was hit by at least one Ukrainian missile. 

Amid its threats, Moscow continues preparations for a renewed offensive in eastern Ukraine. Fighting also continues in the pummelled southern port city of Mariupol, where locals reported seeing Russian troops digging up bodies. 

Around Kyiv, Andriy Nebytov, the head of Kyiv's regional police force, said bodies were abandoned in the streets or given temporary burials. He cited police data indicating 95 per cent died from gunshot wounds. 

"Consequently, we understand that under the [Russian] occupation, people were simply executed in the streets," Nebytov said. 

More bodies were being found every day, under rubble and in mass graves, he added. The largest number of victims were found in Bucha, where there were more than 350, he said. 

According to Nebytov, utility workers in Bucha gathered and buried bodies in the Kyiv suburb while it remained under Russian control. Russian troops, he added, were "tracking down" people who expressed strong pro-Ukrainian views. 

More violence could be in store for Kyiv after Russian authorities accused Ukraine of wounding seven people and damaging about 100 residential buildings with airstrikes in Bryansk, a region bordering Ukraine. Authorities in another border region of Russia also reported Ukrainian shelling Thursday. 

"The number and the scale of missile attacks on objects in Kyiv will be ramped up in response to the Kyiv nationalist regime committing any terrorist attacks or diversions on the Russian territory," Russian Defence Ministry spokesman Igor Konashenkov said. 

Ukrainian officials have not confirmed striking targets in Russia, and the reports could not be independently verified. 

A man looks at his burned car after a Russian attack in Kharkiv, Ukraine, Friday, April 15, 2022. Photo / AP 

However, Ukrainian officials said their forces did strike a key Russian warship with missiles. A senior US defence official backed up the claim, saying the US now believes the Moskva was hit by at least one, and probably two, Neptune missiles. Earlier, the Pentagon said it couldn't confirm the cause of the large fire aboard the guided-missile cruiser. The official spoke on the condition of anonymity to discuss an intelligence assessment. 

The Neptune is an anti-ship missile recently developed by Ukraine based on an earlier Soviet design. 

The Moskva, named for the Russian capital, then sank while being towed to port on Thursday after suffering heavy damage. Though Moscow did not acknowledge any attack, saying only that a fire had caused ammunition on board to detonate, the loss of the ship represents an important victory for Ukraine and a symbolic defeat for Russia. 

The Moskva had the capacity to carry 16 long-range cruise missiles. The last time such a large warship sank in combat was 1982, when a British submarine torpedoed an Argentine navy cruiser called the ARA General Belgrano during the Falklands War, killing more than 300 sailors. 

The sinking reduces Russia's firepower in the Black Sea, although military analysts disagreed on the event's significance to the course of the war. Either way, the loss was viewed as emblematic of Moscow's fortunes in a seven-week invasion widely seen as a historic blunder following the retreat from the Kyiv region and much of northern Ukraine. 

"A 'flagship' Russian warship is a worthy diving site. We have one more diving spot in the Black Sea now. Will definitely visit the wreck after our victory in the war," Ukrainian Defence Minister Oleksiy Reznikov tweeted on Friday in a boast. 

Elsewhere, Russia used missiles to destroy a facility for the repair and production of missile systems in Kyiv, Konashenkov said. 

In his nightly address on Thursday, Ukrainian President Volodymyr Zelenskyy told Ukrainians they should be proud of having survived 50 days under Russian attack when the invaders "gave us a maximum of five". 

Vadim Krikun is treated in the hallway of his apartment building after a Russian attack in Kharkiv, Ukraine, Friday, April 15, 2022. Photo / AP 

Russia's warning of renewed airstrikes did not stop Kyiv residents from taking advantage of a sunny and slightly warmer spring Friday as the weekend approached. More people than usual were out on the streets, walking dogs, riding electric scooters and strolling hand in hand. 

In one central park, a small group of people including a woman draped in a Ukrainian flag danced to the music of a portable speaker. 

Residents reported hearing explosions in parts of Kyiv overnight, but it was not clear what sites were targeted. 

A renewed bombardment could mean a return to the steady wail of air raid sirens heard during the early days of the invasion and to fearful nights sheltering in subway stations. Tentative signs of pre-war life have resurfaced in the capital after Russian troops failed to capture the city and retreated to concentrate on eastern Ukraine, leaving behind evidence of possible war crimes. 

News about the Moskva overshadowed Russian claims of advances in the southern port city of Mariupol, which Moscow's forces have blockaded since the early days of the invasion. Dwindling numbers of Ukrainian defenders have held out against a siege that has come at a horrific cost to trapped and starving civilians. 

Mariupol's mayor said this week more than 10,000 civilians had died and the death toll could surpass 20,000. Other Ukrainian officials have said they expect to find evidence in Mariupol of atrocities against civilians like the ones discovered in Bucha and other towns outside Kyiv. 

Firefighters extinguish a fire at a factory after a Russian attack in the outskirts of Kharkiv, Ukraine, Friday, April 15, 2022. Photo / AP 

The Mariupol City Council said on Friday locals reported seeing Russian troops digging up bodies that were buried in residential courtyards and not allowing new burials "of people killed by them". 

"Why the exhumation is being carried out and where the bodies will be taken is unknown," the council said on the Telegram messaging app. 

Fighting continued in industrial areas and the port, and Russia has for the first time used the Tu-22М3 long-range bomber to attack the city, said Oleksandr Motuzyanyk, a spokesman for the Ukrainian Ministry of Defence. 

Mariupol's capture would allow Russian forces in the south, which came up through the annexed Crimean Peninsula, to fully link up with troops in the Donbas region, Ukraine's eastern industrial heartland and the target of the looming offensive. 

Moscow-backed separatists have fought Ukrainian forces in the Donbas since 2014, the same year Russia seized Crimea from Ukraine. Russia has recognised the independence of two rebel-held areas of the region. 

Although it's not certain when Russia will launch the full-scale campaign, a regional Ukrainian official said on Friday seven people died and 27 were injured after Russian forces opened fire on buses carrying civilians in the village of Borovaya, near the northeastern city of Kharkiv. The claim could not be independently verified. 

Ukrainian Nicolai, 41, cries as he says goodbye to his daughter Elina, 4, and his wife Lolita, on a train bound for Poland fleeing from the war. Photo / AP 

Dmytro Chubenko, a spokesman for the regional prosecutor's office, told Ukraine's Suspilne news website Ukrainian authorities had opened criminal proceedings in connection with a suspected "violation of the laws and customs of war, combined with premeditated murder". 

Kharkiv regional governor Oleh Sinehubov said shelling of a residential part of the city killed seven people, including a 7-month-old child, and wounded 34. 

A large explosion also struck the eastern city of Kramatorsk, where a missile strike on a train station a week earlier killed more than 50 people as thousands heeding warnings to evacuate the Donbas area waited to leave. 

Associated Press journalists in Kramatorsk heard the sound of a rocket or missile and then the blast, followed by sirens wailing on Friday. It was not immediately clear what was hit or whether there were casualties. A day earlier, a factory in the same city was hit by an airstrike. 

The Russian Defence Ministry said Russian strikes in the Kharkiv region "liquidated a squad of mercenaries from a Polish private military company" of up to 30 people and "liberated" an iron and steel factory in Mariupol. The claims could not be independently verified. 

- Adam Schreck, Robert Burns and Yescia Fisch AP