Ukraine did not immediately comment on the announcement.

Diplomatic efforts to end the fighting have accelerated in recent weeks, with the two sides meeting for their first face-to-face talks in over three years earlier this month in Istanbul.

"Our delegation, led by Vladimir Medinsky, is ready to present this memorandum to the Ukrainian delegation and provide the necessary explanations during a second round of direct talks in Istanbul on Monday, June 2," Russian Foreign Minister Sergei Lavrov said.

"I would like to once again express our gratitude to our Turkish partners for providing a hospitable venue, as confirmed yesterday by Turkish Foreign Minister Hakan Fidan during his visit to Moscow," Lavrov added.

Medinsky, a Russian political scientist and former culture minister, led Russia's negotiating team during the first round of talks on May 16.

US President Donald Trump has put pressure on both sides to broker an end to the three-year conflict.