The United Nations Security Council is due to vote on Sunday to call for a rare emergency special session of the 193-member UN General Assembly on Russia's invasion of Ukraine, which would be held on Monday, diplomats said.

The vote by the 15-member council is procedural so none of the five permanent council members - Russia, China, France, Britain and the United States - can wield their vetoes. The move needs nine votes in favour and is likely to pass, diplomats said.