Kherson has become the first Ukrainian city to fall to Russia, with a Ukrainian official confirming it was now under the "complete control" of Putin's forces. 

Kherson – considered to be a strategically key centre – has around 300,000 residents, and its capture could enable Russia to control a significant chunk of the southern coastline and allow troops to head west towards the port city of Odessa. 

According to the New York Times, mayor Igor Kolykhaev confirmed Russian troops had encircled the city with Ukrainian forces retreating to the nearby city of Mykolaiv. 

Russia has claimed victory over the city, with Defence Ministry spokesman Igor Konashenkov stating that Kherson was under the "complete control" of Russian forces. 

Flames and smoke rise from a damaged gym following shelling in Kyiv, Ukraine. Photo / AP 

This satellite image provided by Maxar Technologies shows a close up of destroyed factory building west of Chernihiv, Ukraine. Photo / AP 

He claimed in a statement that Russian authorities were in talks with Ukrainian leaders and that Kherson's infrastructure was still operational. 

Russia accused of 'full-scale genocide' 

Meanwhile, the mayor of Mariupol has given a powerful interview, accusing Russia of carrying out "genocide" against his people. 

The city has been among the hardest hit by Russian troops, with hundreds feared dead after hours of non-stop bombardment. 

Mayor Vadym Boychenko told Ukraine's 1+1 TV Channel that Russian troops had prevented citizens from fleeing to safety. 

"There's been colossal destruction of residential infrastructure, there are many wounded and unfortunately many civilian dead, women, children, old people," he said. 

This satellite image provided by Maxar Technologies shows a close up of destroyed military vehicles and homes at a residential area south of Antonov airport in Bucha, Ukraine. Photo / AP 

"A full-scale genocide of the Ukrainian people is underway. 

"You have to understand that the occupation forces of the Russian Federation have done everything to stop the exit of civilians from our city of half a million people. 

"Our railway link has been cut – they even went to the railway station and fired on our diesel locomotives so that people can't be evacuated. 

"So their mission is to destroy us, they have no intention of helping civilians." 

Mariupol is seen as especially strategic for the invading forces, as it would allow pro-Russian separatists to link up with troops positioned in Crimea.