Russian forces are trying to blockade the southeastern Ukrainian port city of Mariupol, knocking out power, water and heating supplies with bombardment that is preventing residents from fleeing, local authorities said on Thursday.

As Russia's invasion of Ukraine enters its second week, the port city is seeing some of the fiercest fighting with constant shelling for the past 24 hours, Mayor Vadym Boichenko said in a video broadcast. read more

The city authorities likened the Russian onslaught to Nazi Germany's protracted deadly siege of the then-Soviet city of Leningrad during World War Two.

"Mariupol remains under fire. Women, children and the elderly are suffering. We are being destroyed as a nation. This is genocide of the Ukrainian people," the city's council said in a statement.

Relatives of people still in the city told Reuters they had not heard from their loved-ones due to the power outage and were desperate for news.

"They are now in the very centre of hostilities and I am far from them and cannot help," said 30-year-old driver Dmitriy, who had travelled abroad for work just before war broke out, leaving his wife and young son in Mariupol.

"I've not been able to reach them for around 24 hours," he said by message. "We all lived a peaceful life, working, studying, making plans, until life turned completely upside down."