Each side is due to meet on Friday with Marco Rubio, the US Secretary of State, and Turkey's foreign minister, Hakan Fidan, but still without any broader meeting planned.

Putin's absence punctured hopes of a breakthrough in peace efforts that were given a push in recent months by the Trump administration and Western European leaders.

Ukrainian President Volodymyr Zelensky has said he will travel to Turkey's capital Ankara to meet President Recep Tayyip Erdogan and will be available for direct talks with his Russian counterpart, Vladimir Putin, in Istanbul on Thursday.