Here are the latest developments in the war in Ukraine:

Sumy regional governor Dmytro Zhyvytsky tells residents in the northern Ukrainian town of Novoselytsya to shelter after an ammonia "leak" at a nearby chemical factory. The area has seen heavy fighting.

Russia gives the besieged city of Mariupol until 5:00 am on March 21 to surrender, warning that more than a "court martial" awaits those who refuse.

Ukraine's Deputy Prime Minister Iryna Vereshchuk rejects the ultimatum, telling local media "there can be no talk of surrendering weapons".

US President Joe Biden will travel to Poland on Friday to meet President Andrzej Duda, the White House says.

Ukrainian authorities accuse Russia of bombing a Mariupol art school where some 400 people, including women and children, had been sheltering.

Mariupol officials claim Russian forces have forcibly transported around a thousand residents to Russia and stripped them of their Ukrainian passports -- a potential war crime.

The mayor of the encircled northern city of Chernigiv says dozens of civilians have been killed by "indiscriminate artillery shelling", and that a hospital has been hit.

"The city is suffering from an absolute humanitarian catastrophe," he adds.

At least one person is killed when Russian forces shell a shopping centre in the Ukrainian capital Kyiv, the city's mayor says.

Zelensky calls for urgent talks with Russia, adding Jerusalem is perhaps "the right place for finding peace. If this is possible."

Ukrainian soldiers carried a comrade's body out of debris Saturday at a military school hit by Russian rockets in Mykolaiv.
Ukrainian soldiers carried a comrade's body out of debris Saturday at a military school hit by Russian rockets in Mykolaiv. AFP / BULENT KILIC

Turkish Foreign Minister Mevlut Cavusoglu says Russia and Ukraine have made progress in negotiations and are "close to an agreement".

Turkey says it is also ready to host a meeting between Ukrainian President Volodymyr Zelensky and Russian President Vladimir Putin.

Slovenian Prime Minister Janez Jansa announces the country's diplomats will return to Kyiv "soon" and calls on other EU members to do the same. Ukraine "needs direct diplomatic support", he says.

Russia says it has again fired hypersonic missiles in Ukraine, destroying a fuel storage site in the country's south.

US Defence Secretary Lloyd Austin says if confirmed, the use of the weapons would not be a "game changer".

China's ambassador to the US says his country is not sending weapons to Russia for use in Ukraine, but he does not definitively rule out the possibility Beijing might do so in the future.

Pope Francis denounces the "senseless massacre where every day slaughter and atrocities are repeated" in Ukraine, appealing to the international community to stop the war.

"There is no justification for this," he adds.

Ukrainian officials say one of Europe's biggest iron and steel works, Azovstal, has been badly damaged by Russian forces.

Australia bans all exports of alumina and bauxite to Russia while pledging more weapons and humanitarian assistance to Ukraine. Russia relies on Australia for 20 percent of its alumina.

Ten million people -- more than a quarter of the population -- have now fled their homes in Ukraine due to Russia's "devastating" war, the United Nations refugees chief says Sunday. More than 3.3 million of them have escaped the country.