Children react as they take shelter in a bunker said by Ukraine's Azov Battalion to be in Azovstal steelworks in Mariupol on Saturday. Reuters

The video was released by the Azov battalion, which was set up by pro-Ukrainian nationalists in 2014, later incorporated as a regiment in Ukraine's national guard and has played a prominent role in the defence of Mariupol.

Reuters could not independently verify where or when the video was shot. Somebody speaking in the video mentions that the date is April 21.

The video shows soldiers bringing food for civilians who the battalion says are sheltering in the Azovstal complex.

Ukrainian woman Tetyana Davydova holds her sons at a shelter for refugees in the town of Novomoskovsk. Reuters

A woman holding a toddler said people in the plant were running out of food: "We really want to go home," she said.

Russian forces were hitting the Azovstal complex with air strikes and trying to storm it, presidential adviser Oleksiy Arestovych said on Saturday, although Moscow had said this week that it would blockade the plant and not attempt to take it. More than 1,000 civilians are in the plant along with troops defending it, according to Ukrainian authorities.

One unnamed boy in the video said he was desperate to get out after being in the plant for two months.

"I want to see the sun because in here it's dim, not like outside. When our houses are rebuilt we can live in peace. Let Ukraine win because Ukraine is our native home," he said.

A mother and her son speak to journalists in an area controlled by Russian-backed separatist forces in Mariupol. AP

The video showed women wearing uniforms with the Azovstal design, which Reuters verified, matched in file images.

One woman said she had been sheltering in the steel works since Feb.27, just days after Russia launched its invasion of Ukraine.

"We are relatives of the workers. But this seemed to be the safest place at the time we came here, this was when our house came under fire and became uninhabitable," she said.

A woman reads a book at a shelter for refugees in the town of Novomoskovsk. Reuters

Russian forces have besieged and bombarded Mariupol since the early days of the war, leaving a city that is usually home to more than 400,000 people in ruins. A new attempt to evacuate civilians failed on Saturday, an aide to Mariupol's mayor said.

Reuters