Russian troops also attacked the massive Azovstal steel factory in Mariupol on Wednesday, an aide to the mayor of the port city, which was conquered mainly by Russia, said.
According to him, an agreement has not been reached on evacuation routes for civilians to flee to safe parts of Ukraine.
The factory complex with its catacombs is estimated to house more than 2,000 Ukrainian fighters. According to Ukraine, there are also about a thousand civilians in bunkers, many of them women and children.
Russian President Vladimir Putin last week ordered the attack on the colossal factory site to stop, but the complex is under constant attack. There have also been storms in recent days.