STORY: If Moscow captures Mariupol, it would be the first big city to fall.

Footage taken near the plant by Reuters on Friday showed damaged plant and numerous dead bodies in the streets nearby.

Ukrainian defenders are mainly believed to be holding out in Azovstal, another huge steel works.

Ukraine's defence ministry spokesman Oleksandr Motuzyanyk said on Friday that for the first time since the start of its invasion, Russia used long-range bombers to attack the Ukrainian forces in the city.