A diplomatic source told AFP that a resolution condemning Russia's invasion was being put before the meeting, but that a vote on the resolution would likely only come on Thursday.

Ukraine has four active nuclear power plants, providing about half the country's electricity, as well as stores of nuclear waste such as the one at Chernobyl.

Poland and Canada requested the International Atomic Energy Agency (IAEA) board of governors meeting to discuss the implications of the invasion, including fears over what could happen if nuclear-related sites are damaged in the fighting.

Chernobyl was the site of the worst nuclear accident in history in 1986 and last Thursday the site fell to Russian troops.

"The best action to ensure the safety and security of Ukraine's nuclear facilities and its people would be for this armed conflict to end now," IAEA Director General Rafael Grossi told the meeting.

This war, he told reporters, was the first time there had been "an ongoing military conflict taking place in a country that has a vast nuclear programme".

Given the current composition of the board of governors, some form of resolution condemning the invasion is likely to be approved by most of the states.

Although only the 35 board members have a vote, more than 50 IAEA member states requested to speak at the meeting.

The US delegation at the meeting had a Ukrainian flag affixed to their desk bearing the words: "Today we are all Ukraine".

In his address to the meeting American diplomat Louis L. Bono condemned Russia's "wanton and unprovoked aggression" against its neighbour.

Mikhail Ulyanov, Russia's ambassador to the UN in Vienna, told AFP that Moscow had received support from Egypt and China at the meeting and denied that Russia was diplomatically isolated.

He criticised the proposed resolution as a "shameful","poor quality document" which contained "factual errors".

On Monday, Grossi said he had received reports that Russian soldiers were close to the Zaporizhzhia station in eastern Ukraine.

Grossi has warned that any "accident involving the nuclear facilities in Ukraine could have severe consequences for public health and the environment".