The Kremlin said on Tuesday it was "sure" that Russian-backed separatist leaders in the Donbas would be willing to listen to an appeal from Britain over the fate of two Britons sentenced to death for fighting for Ukraine.
Kremlin spokesperson Dmitry Peskov told reporters in a conference call that London had not contacted Moscow about the issue.
A court in the breakaway Donetsk People's Republic (DPR) in eastern Ukraine last week sentenced Britons Aiden Aslin and Shaun Pinner and Moroccan Brahim Saadoun to death, saying they were guilty of "mercenary activities".
Their families deny that the trio, who were contracted by the Ukrainian armed forces, were mercenaries.
Britain has so far declined publicly to raise the issue with authorities in the DPR.
The territory, much of which remains under Ukrainian control, is internationally recognised as part of Ukraine, except by Russia - which considers it an independent state. Dealing directly with DPR leaders might be seen as de facto recognition.
British Foreign Secretary Liz Truss said earlier on Tuesday that that the best route to secure the release of Aslin and Pinner was "through the Ukrainians", but that she would do "whatever it takes".
London has called the death sentences a "sham ruling" and said the proceedings were akin to a Soviet-era show trial.
Authorities in the DPR said the men had a month to launch an appeal. Their lawyers said they would do so and Kyiv has pledged to try to secure their release through a prisoner exchange with Russia.
(Reporting by Reuters; Editing by Kevin Liffey)