"They agreed on the need to seize on this moment with an acceleration of global military and diplomatic support to Ukraine," a spokesperson for Sunak said.

"The prime minister outlined the UK's ambition to intensify our support to Ukraine, including through the provision of Challenger 2 tanks and additional artillery systems."

There have been a number of media reports suggesting that Britain was in discussions with Ukraine to deliver the Challengers, the British Army's main battle tank, to help the country fight invading Russian forces.

However, the British government has repeatedly said no final decision had been taken.

"The prime minister and President Zelenskiy welcomed other international commitments in this vein, including Poland's offer to provide a company of Leopard tanks," Sunak's spokesperson said.

"The prime minister stressed that he and the whole UK government would be working intensively with international partners to deliver rapidly the kind of support which will allow Ukraine to press their advantage, win this war and secure a lasting peace."

(Reporting by Michael HoldenEditing by Mark Heinrich and Angus MacSwan)