Following a phone call last week, the Russian and US leaders Vladimir Putin and Donald Trump announced they would meet in Budapest for talks on resolving the war in Ukraine, triggered by Moscow’s February 2022 all-out offensive.

Russian foreign minister Sergei Lavrov and US counterpart Marco Rubio spoke on Monday to discuss preparations for the summit and are expected to meet in person to finalise details.

Trump said the meeting with Putin could take place within two weeks, though that timeline appears to be slipping away.

Russia’s deputy foreign minister Sergei Ryabkov said on Tuesday it was “premature to talk about the schedule” of the preparatory Lavrov-Rubio meeting.

“Neither before the phone call nor during yesterday’s call was the meeting specifically raised,” Ryabkov was quoted as saying by Russian state news agencies.

“Any such significant contact should be properly prepared,” Ryabkov said, adding that “a ‘homework’ phase” must be first completed.

Trump, who previously claimed he could settle the Ukraine war in a matter of hours, has shown frustration with both Moscow and Kyiv over the failure to broker peace.

Putin has rejected multiple calls for a ceasefire and stuck to a list of hardline demands that Kyiv sees as unacceptable.

Ukrainian President Volodymyr Zelensky, who is pushing to attend the summit in Budapest, has ruled out territorial concessions.

Several rounds of direct negotiations between Ukrainian and Russian teams in Istanbul have yielded nothing beyond prisoner exchanges and the repatriation of the bodies of soldiers killed in combat.

A previous summit between Putin and Trump in Alaska ended early with no breakthrough towards a peace deal.

Ukraine says a meeting between Putin and Zelensky is needed to make progress, but the Kremlin has ruled out talks with the Ukrainian leader until a peace deal is practically agreed.