KYIV: The Ukrainian military said Tuesday that Russian forces had launched an offensive on the besieged Azovstal steel plant where Kyiv’s forces are holed up in the southern city of Mariupol.

“A powerful assault on the territory of the Azovstal plant is underway with support from armoured vehicles and tanks,” Sviatoslav Palamar, deputy commander of Ukraine’s Azov military unit said in a statement on social media.

Russian forces are also attempting “to land a large number of infantry by boat,” he said.

“We will do everything we can to repel this assault, but we call for immediate measures to evacuate civilians who are on the territory of the plant,” he said.

The Russian army said earlier Tuesday that its forces and pro-Moscow separatists were using artillery and planes to target Azovstal where Ukrainian fighters are making their last stand.

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The Russian defence ministry accused members of the Azov battalion and other Ukrainian troops of using a pause in fighting to once again take up their combat positions at the plant.

“Using artillery and aircraft, units of the Russian army and the Donetsk People’s Republic are beginning to destroy” the “firing positions” of the Ukrainian troops, the defence ministry said in a statement carried by Russian news agencies.

Mariupol is among the most battered cities in Ukraine.

The United Nations announced Tuesday that 101 civilians had been successfully evacuated from the tunnels of the Azovstal plant in a joint operation with the Red Cross.