Ukrainian President Volodymyr Zelensky accused Russian President Vladimir Putin of being too "afraid" to turn up for face-to-face peace talks in Istanbul, as direct negotiations erupted in accusations that Russia made "unacceptable demands".

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.

Russian President Vladimir Putin’s snub of Thursday’s peace talks in Turkey shows how “unserious” the Kremlin is about ending its war, Ukrainian President Volodymyr Zelensky told reporters in Ankara.