“The (Russian) occupiers are in all parts of the city and are very dangerous,” Gennady Lakhuta, head of the regional administration, wrote on messaging service Telegram late Wednesday.

Another key Ukrainian port, Berdiansk, has already been seized by Russian troops, while Mariupol has repelled attacks “with dignity,” according to that city´s mayor, Vadim Boichenko.

Russian forces have also bombarded Ukraine’s second-biggest city Kharkiv, prompting comparisons to the massacres of civilians in Sarajevo in the 1990s.

After days of intense fighting, hundreds of civilians have been killed, while around one million people have fled Ukraine since the invasion began, triggering punishing Western sanctions intended to cripple Russia´s economy.