Meanwhile, Vladimir Putin’s spokesman Dmitry Peskov ruled out a meeting between the Russian president and his Ukrainian counterpart until Kiev had “done its homework on the negotiations and agreed on the results”.
He also claimed that a ceasefire would be used by the Ukrainian army to regroup, saying, “It would be used to continue the attacks on the Russian army.”
Since the start of the war, teams from Russia and Ukraine have met several times in Belarus, but Peskov said there was “no substantial movement” despite recent reports that the countries were close to an agreement.
Along with these talks are moves by Naftali Bennett, the Israeli Prime Minister, and Recep Tayyip Erdogan, the President of Turkey, to bring Putin and Mr Zelensky together for negotiations.
Last week, Mr Zelensky offered the prospect of Ukraine accepting never to join NATO, a key Russian demand, as the basis of a peace deal.
Alexander Rodnyansky, a presidential adviser to Mr Zelensky, has told Politico that neutrality is a “relatively easy” issue in peace talks compared to the status of the Moscow-backed separatist regions that seceded in 2014 when Russia annexed Crimea.
“Anything that has to do with our sovereignty in territory, of course, that’s not going anywhere,” he said.
In the US, officials said Putin appeared to have returned to a “Plan B” after failing to take Kiev and overthrow the Ukrainian government in a lightning-fast attack.