Alexander Fomin leaves after a meeting with Ukrainian negotiators in Istanbul, Turkey, on Tuesday. Reuters

Russia said on Tuesday it would sharply scale back military activity around Ukraine's capital Kyiv and the northern city of Chernihiv, in the most tangible sign yet of progress towards a peace deal.

Deputy Defence Minister Alexander Fomin gave the undertaking after talks between delegations from the two countries in Istanbul.

"In order to increase mutual trust and create the necessary conditions for further negotiations and achieving the ultimate goal of agreeing and signing (an) agreement, a decision was made to radically, by a large margin, reduce military activity in the Kyiv and Chernihiv directions," Fomin told reporters.

He did not refer to the eastern and southern parts of Ukraine where Russian forces are also conducting major offensives but have struggled to make headway.

Russia's chief negotiator, Vladimir Medinsky, said this was one of two steps Moscow was taking to de-escalate the 34-day-old conflict.

He said the other was that Russia would agree to a meeting between presidents Vladimir Putin and Volodymyr Zelenskiy to take place simultaneously if and when a peace treaty was initialled by their foreign ministers.

Previously, Moscow had said that a presidential meeting could only take place at a later point.

Ukrainian negotiators said they had proposed at the latest round of talks with Russia that Ukraine adopt neutral status in exchange for security guarantees, meaning Kyiv would not join military alliances or host military bases.

Medinsky said: "These proposals will be considered in the near future, reported to the president (Putin), and our response will be given."

Fomin said Russia had also called on Ukraine to eliminate what he called torture of captured Russian prisoners.

Ukraine checks all information concerning the treatment of prisoners and will take appropriate legal action if soldiers are found guilty of any violation, the deputy head of the general staff of Ukraine's armed forces said on Tuesday.

Reuters