Putin said Kyiv was pursuing "a destructive line" and that it had "bet on the intensification of hostilities with the support of Western sponsors, who are ramping up supplies of weapons and military equipment," the Kremlin said.

He also accused Kyiv of rejecting his offer to halt fighting on Christmas Day which is marked on January 7 in Russia and Ukraine. Ukraine at the time dismissed the halt as a Russian ploy to gain time to regroup forces.

Britain this weekend pledged 14 Challenger 2 tanks to Ukraine, which would make it the first Western country to supply heavy tanks following pleas from Kyiv.

NATO Secretary General Jens Stoltenberg meanwhile said this weekend that Ukraine could expect more heavy weapons following Kyiv's requests.

The Turkish presidency for its part said that "President Erdogan reiterated that Turkey is ready to facilitate and mediate the establishment of a lasting peace between Russia and Ukraine."

The Kremlin also said Putin and Erdogan discussed an exchange of Russian and Ukrainian prisoners of war, including wounded soldiers.