A senior Russian diplomat said on Friday that talks on security guarantees for Russia cannot take place while NATO instructors and "mercenaries" remain in Ukraine, and while Western arms supplies to the country continue.
Reuters said the head of the Russian Foreign Ministry's North America department Alexander Darchiev came up with the statement in an interview with the Russian state-owned news agency TASS.
He said talks would be premature "until the flood of weapons and financing for the (Ukrainian President Volodymyr) Zelenskiy regime stops, American and NATO servicemen/mercenaries/instructors are withdrawn".
Russia typically refers to foreign volunteers fighting with the Ukrainian army as "mercenaries" and has convicted captured foreign fighters of acting as such.
Russian officials have increasingly stressed their openness to talks on Ukraine in recent weeks, even as they have emphasised that they do not believe Zelenskiy is interested in a peaceful settlement.
In his comments, Darchiev said that talks would also need to be preceded by "recognition of the realities we have defined on the ground", an apparent reference to Russia's control of parts of eastern and southern Ukraine.