Russian forces have reportedly entered the largest hospital in the southern Ukrainian city of Mariupol and are preventing doctors and patients from leaving the building.

Donetsk Oblast Governor said on Tuesday afternoon that Russian forces "drove 400 people from neighbouring houses to the Regional Intensive Care Hospital and they can’t leave".

Pavlo Kirilenko, head of the Donetsk regional military administration, said: "It is impossible to get out of the hospital. There is a heavy shooting, we sit in the basement.

"Vehicles have not been able to drive to the hospital for two days. High-rise buildings are burning around… Russians forced 400 people from neighbouring houses to come to our hospital. We can't leave."

Russian forces are apparently firing at the windows of the hospital in an effort to trigger a response from Ukrainian soldiers, according to the Media Initiative for Human Rights.

A human rights organisation as said the Russian military are "threatening to shoot" at hostages who attempt to escape adding that "patients who risked escape from captivity returned with bullet wounds".

Mariupol is the centre of a growing humanitarian crisis, as food and medical supplies run out and aid is not being allowed in. The city has been under constant Russian shelling, with an estimated 350,000 residents trapped.