Horrific scenes of people being treated in darkness as others dig away at rubble have been shown inside a shelled makeshift hospital in a Mariupol steel works.
A desperate battle has been raging for weeks in the strategic southern Ukrainian city of Mariupol where fighters are refusing to surrender and Russian shells have reduced it to ruins.
While Russia has claimed most of the city, Ukrainians are still holding onto the massive Azovstal steelworks.
Now a video has been shared by the far-right Azov Brigade believed to be from a military field hospital inside the steel plant after a further Russian bombardment.
Haunting images show scared people sheltering in darkness following the blast with the room lit up by a red light. Someone attempts to pour water on an injured person while another can be seen digging through rubble.
There are believed to have been 600 people injured from the attack including children and elderly people while medical supplies have run out.
Major Serhiy Volyna, commander of the 36th Brigade of the Ukrainian Army, said that the hospital had received a direct hit.
The Ukraine marines commander told Sky News : "The situation is difficult. About 600 people have wounds of different degrees of gravity. We have wounded civilians, 100 of them .... more than 50 children and elderly people. As for medical support, it is absent. Last night, there was a direct hit by an aerial bomb on the shelter of the military hospital.
"I can say that the city is beyond the brink of a humanitarian catastrophe. It has been totally erased from the face of the earth. The Ukrainian garrison of Mariupol is holding defence lines at the Azovstal works and on the approaches to it. The rest of the territory is controlled by Russian troops."
He said that there had been continual strikes on the steel works and that tanks and other firearms have been hitting residential buildings from point blank range.
Major Volyna said: "The operation room was completely destroyed, just field conditions, we can no longer operate on the wounded. The situation is critical. Medical support is absent. The conditions in which servicemen and civilians, children and the elderly are trying to survive are simply horrible."
It comes as UN Secretary General Antonio Guterres met with Ukraine leader Volodymyr Zelenskiy in Kyiv where they focused in part on evacuating Ukrainian fighters and civilians holed up inside the steel plant.
Russian President Vladimir Putin has agreed in principle to UN and Red Cross involvement in evacuating the plant during separate talks in Moscow with Guterres on Tuesday. Ukrainian officials worry Russia wants to capture those trapped inside, an allegation Moscow denies.
The West believes battles for Mariupol and other eastern and southern areas may determine the war's outcome. Russian forces are now entrenched in the east, where Moscow-backed separatists have held some territory since 2014, and also hold a swathe of the south they seized in March.
Ukraine's general staff said Russia was stepping up its military assault in the Donbas.
"The enemy is increasing the pace of the offensive operation. The Russian occupiers are exerting intense fire in almost all directions," it said.
