Ukrainian President Volodymyr Zelensky said on Tuesday the Russian siege of the port city of Mariupol constituted a "crime against humanity".
"What the Russian troops are doing to Mariupol is a crime against humanity, which is happening in front of the eyes of the whole planet in real time," Mr. Zelensky told the Danish parliament in a video address.
He accused Russian forces of blowing up shelters despite knowing that civilians were hiding in them.
The President's comments came as Ukrainian and Russian negotiators held face-to-face talks in Istanbul, under the shadow of shock allegations that delegates were poisoned at a previous round of negotiations.
Russian forces have encircled the southern Ukrainian city of Mariupol and have embarked on a steady and indiscriminate bombardment, trapping an estimated 160,000 people with little food, water or medicine.
At least 5,000 people have already died, according to one senior Ukrainian official who estimated the real toll may be closer to 10,000 when all the bodies are collected.
During his address to Danish parliamentarians, Zelensky also said more deaths had been confirmed after a Russian strike hit the regional government building in the southern Ukrainian city of Mykolaiv.
"As far as we know now seven people were killed, 22 were wounded, and people are still going through the rubble," Zelensky said.
"There were no military ambitions in Mykolaiv, the people in Mykolaiv presented no threat to Russia. And even then, like all the Ukrainians, they became the targets for the Russian troops", he said.
Earlier on Tuesday, AFP journalists on the scene in the aftermath of the attack said the bodies of two people were pulled from debris.
The International Criminal Court on March 3 opened an investigation into war crimes in Ukraine.
