An art school where about 400 people had taken refuge in the besieged Ukrainian port city of Mariupol has been bombed by the Russian military, according to officials in the area.

Local authorities said on Sunday that the school building was destroyed and people may be trapped under the rubble. There was no immediate word on casualties.

Russian forces had on Wednesday bombed a theatre in Mariupol where civilians took shelter. Local officials said 130 people were rescued but many more could remain under the debris.

Mariupol, a strategic port on the Azov Sea, has been encircled by Russian troops, cut off from energy, food and water supplies and faced a relentless bombardment. Local authorities have said the siege has killed at least 2,300 people and some of them had to be buried in mass graves.

Ukrainian President Volodymyr Zelensky has said the siege of Mariupol will go down in history for what he said were war crimes committed by Russian troops.

“To do this to a peaceful city, what the occupiers did, is a terror that will be remembered for centuries to come,” Mr Zelensky said in a video address to the nation.

Mariupol police officer Michail Vershnin, speaking from a rubble-strewn street in a video addressed to Western leaders, said: “Children, elderly people are dying. The city is destroyed and it is wiped off the face of the earth.”

Officials in the city say nearly 40,000 people have fled over the past week – almost 10% of its 430,000 population.

The city council said the 39,426 residents safely evacuated in their own vehicles, using a humanitarian corridor via Berdyansk to Zaporizhzhia.

The fall of Mariupol, the scene of some of the war’s worst suffering, would mark a major battlefield advance for the Russians, who are largely bogged down outside major cities more than three weeks into the biggest land invasion in Europe since the Second World War.

Meanwhile in the eastern city of Kharkiv, officials say at least five civilians have been killed in the latest Russian shelling.

Regional police in the city, the second largest in Ukraine, said the victims of the artillery attack early on Sunday included a nine-year-old boy.

Kharkiv has been besieged by Russian forces since the start of the invasion and, like Mariupol, has come under a relentless barrage.

Elsewhere, Mr Zelensky has ordered 11 political parties with links to Russia, the largest of which has 44 out of 450 seats in the country’s parliament, to suspend activities during the period of martial law.

“Activities by politicians aimed at discord and collaboration will not succeed,” he said.

Earlier in a speech to thousands of anti-war protesters in the Swiss city of Bern, he called on the Swiss government to freeze the bank accounts of all Russian oligarchs.

Swiss public broadcaster SRF reported that Mr Zelensky said: “In your banks are the funds of the people who unleashed this war. Help to fight this. So that their funds are frozen… It would be good to take away those privileges from them.”

The Ukrainian president also criticised the Swiss multinational food conglomerate Nestle, which has decided not to withdraw from Russia for the time being, unlike many other international companies.

Mr Zelensky’s speech was dubbed into German. When he called for the blocking of oligarchs’ accounts, great applause erupted.