Russian forces have relaunched their attack on Ukrainian fighters inside the Azovstal Iron and Steel Works in the besieged city of Mariupol.
Troops began a fresh bombardment of the factory on Tuesday May 3 after accusing Ukrainian fighters of violating a ceasefire agreement.
The Ukrainian military said that armoured vehicles and ground troops were also being mobilised to attack the factory.
"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.
"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."
Journalists reported that shooting could be heard from the area, while video from the scene showed columns of smoke rising from the plant.
“[The Azov Battalion and the Armed Forces of Ukraine] came out of the basement and took up firing positions. Now units from the Russian army and the military of the Donetsk People’s Republic are beginning to destroy these positions using artillery and aircraft,” Russia’s Defense Ministry told the state-run RIA Novosti news agency.
Mariupol, a strategic port on the Sea of Azov, has been under siege by Russian forces for more than two months. Russian fighters now control most of the city, with a handful of Ukrainian soldiers holding the city’s steel plant.
Dozens of civilians are also trapped in the factory’s basements, where they have been sheltering from Russian shelling.
The UN confirmed on Tuesday that 101 civilians, including children, had been were evacuated from the besieged steel plant as part of a "safe passage operation" carried out alongside the Red Cross on May 2.