Russian forces have surrounded Mariupol, and many have entered the city, reports said.
Footage from the city shows devastation and destruction in civilian areas, as well as tanks driving through the streets and apartment buildings being fired at.
According to the Associated Press, the Ukrainian government said that Russian forces on Saturday shelled a mosque in Mariupol sheltering more than 80 people, including children. There were no immediate reports of casualties, AP said.
At the same time, Maxar satellite pictures revealed heavy damage to civilian infrastructure in Mariupol in southern Ukraine.
Earlier this week, Russian forces bombed a maternity and children's hospital in Mariupol.
On Saturday evening, Israeli Prime Minister Naftali Bennett held a lengthy phone conversation with Ukrainian President Volodymyr Zelenskyy. Following the conversation, Zelenskyy tweeted, "Continued dialogue with PM Naftali Bennett. We talked about Russian aggression and the prospects for peace talks. We must stop repressions against civilians: asked to assist in the release of captive mayor of Melitopol and local public figures. #StopRussia"
Earlier on Saturday, Zelenskyy tweeted: "I spoke with [German Chancellor] Olaf Scholz, [French President] Emmanuel Macron. We discussed countering the aggressor, RF crimes against civilians. I ask my partners to help in releasing the captive mayor of Melitopol. Prospects for peace talks also discussed. We must stop the aggressor together."