Ukrainian and Russian delegations are set to hold their first direct talks on the possibility of ending the war in Ukraine for more than three years.

Ukrainian President Volodymyr Zelenskyy hailed Vladimir Putin's offer for direct peace talks as "a positive sign" but warned that the Russian leader must accept a 30-day ceasefire first.

Russian President Vladimir Putin on Sunday proposed direct talks with Ukraine on May 15 in Istanbul that he said should be aimed at achieving a durable peace and eliminating the root causes of the war.