Speaking at the United Nations Security Council in New York - and sat opposite a Russian representative - the British prime minister accused the state of committing "the greatest violation of the [UN] charter in a generation".

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Sir Keir said: "Russia's invasion of Ukraine is illegal. It threatens global security. And it has caused colossal human suffering.

"Over 35,000 civilians have been killed or injured, six million forced to flee and almost 20,000 Ukrainian children forcefully deported - kidnapped, to put it bluntly.

"Six hundred thousand Russian soldiers have also been killed or wounded in this war. And for what?"

The prime minister questioned how Russia could "show its face in this building", adding: "The UN Charter, which they sit here to uphold, speaks of human dignity - not treating your own citizens as bits of meat to fling into the grinder."

He called for "accountability", telling the council: "There must be accountability. Aggression cannot pay. Borders cannot be redrawn by force.

"Russia started this illegal war. It must end it - and get out of Ukraine."

Sir Keir also reiterated his calls for ceasefires in the conflicts between Israel, Lebanon and Gaza, and in Sudan, saying there needed to be "political solutions that can break repeating cycles of violence".

"In this moment of deepening conflict, the world looks to this council more than ever, to provide leadership for peace, preserve our collective security and protect the most vulnerable," he added.

"The United Kingdom will always play its full part in fulfilling that responsibility."