Serious work on Russia's proposal for a possible peace deal for the Ukraine war is ongoing and a draft has not yet been submitted, Kremlin spokesman Dmitry Peskov said on Monday.

In a phone call with US President Donald Trump last week, Russian President Vladimir Putin said Russia and Ukraine would work on a memorandum relating to a peace accord, prompting new accusations from Kyiv and European governments that Moscow was stalling and had no serious interest in peace.

Russia has rejected such accusations and insists that it has no interest in delaying the peace process.

"The Russian draft of the memorandum has not yet been submitted," Kremlin spokesman Dmitry Peskov told reporters. "Work is continuing. This is a serious draft, a draft of a serious document that demands careful checks and preparation."

Russian Foreign Minister Sergei Lavrov said on Friday that Moscow would be ready to hand Kyiv a draft document outlining conditions for a long-term peace accord once a prisoner exchange agreed at talks in Istanbul was completed.

That swap, which saw both Russia and Ukraine hand over 1,000 people, was completed on Sunday, Russia's defence ministry said.

Peskov said work towards a peace deal would continue based upon agreements reached in Istanbul, with the prisoner exchange as the first stage.