"The Prime Minister said it was now clear Russia was on the back foot, and there was a window for international partners to accelerate efforts to secure lasting peace for Ukraine," Sunak's office said in a statement after he spoke to the leaders of the United States, Germany, France and Italy.

"All the leaders welcomed the strong coordination of military supplies and reflected on the collective international action across the spectrum in support of Ukraine."

(Reporting by Sachin Ravikumar; Editing by Alex Richardson)