"The Ukrainian side has become more realistic in its approach to issues related to the neutral and non-nuclear status of Ukraine but the draft agreement is not ready for submission to a summit meeting," Vladimir Medinsky said on Telegram.

He said he did not share the "optimism" of Ukraine's negotiators on the possibility of talks between Russian President Vladimir Putin and Ukrainian President Volodymyr Zelensky.

Ukraine's top negotiator David Arakhamia said Saturday that Moscow had "verbally" agreed to key Ukrainian proposals, raising hopes that talks to end fighting were moving forward.

He raised the possibility of a meeting between Putin and Zelensky in Turkey, without saying when it might be possible.

Ukraine has offered at the talks to drop its aspirations to join NATO and declare official neutrality, if it has security guarantees from Western countries. It would also pledge not to host any foreign bases.

It has proposed to temporarily put aside the question of Crimea, annexed by Russia in 2014, and two breakaway territories in the eastern Donbas region that Russia has recognised as independent.

Medinsky said Russia's position on Crimea and the Donbas "remains unchanged" and that talks would resume by video conference on Monday.