"Given that the talks on the preparation of an agreement on the neutrality and non-nuclear status of Ukraine have moved into a practical field... a decision has been made to radically... reduce the military activity in the areas of Kyiv and Chernigiv," said Russia's deputy defence minister Alexander Fomin.

Chief negotiator Vladimir Medinsky said there had been a "meaningful discussion" at the talks and that Ukrainian proposals would be put to Russian President Vladimir Putin.

He also said that Putin could meet Ukrainian President Volodymyr Zelensky.

"After today's meaningful discussion we have agreed on and propose a solution, according to which the meeting of the heads of state is possible simultaneously with the foreign ministers initialling the treaty," Medinsky added.

"On the condition of quick work on the agreement and finding the required compromise, the possibility to make peace will become much closer," he said.

Medinsky said the Ukrainian side had presented written proposals, which he said called for Ukraine to become a "permanently neutral state under international security guarantees" aimed at giving it non-nuclear status.

He said that under Kyiv's proposals, these guarantees would not cover Russia-annexed Crimea or the separatist regions of Lugansk and Donetsk, which he said meant Kyiv would give up attempts to return these regions militarily.

According to Medinsky, Ukraine's proposals also include an agreement for it not to enter military alliances or host foreign bases.

He said that Kyiv's proposals were conditional on Russia "not objecting to Ukraine's striving to join the EU".

Kyiv is also calling for the final agreement to be reached at a meeting between Zelensky and Putin, the Russian negotiator said.

Medinsky said in comments reported by state news agency TASS that the proposals were "absolutely not the provisions of an agreement" but "proposals from the Ukrainian side that we consider a constructive step in seeking compromises and that will be considered by Russia."

"A suitable response will be given," he added.

State news agency RIA Novosti reported, citing a source, that the Russian delegation intended to leave Istanbul on Tuesday.

A source in the Russian delegation said "talks will continue via video".