"The situation in Ukraine, which has a steady tendency towards further, uncontrolled escalation, was discussed," by Shoigu and French Defence Minister Sebastien Lecornu, the ministry said.

Later on Sunday, the ministry said Shoigu held phone calls with his Turkish counterpart Hulusi Akar and UK Defence Secretary Ben Wallace.

In the three calls, Shoigu conveyed "concerns about possible provocations by Ukraine with the use of a 'dirty bomb'".

Britain's defence ministry said in a statement that Wallace "refuted" claims that Western countries sought to help Ukraine escalate the conflict and "cautioned that such allegations should not be used as a pretext for greater escalation".

It added that the call was requested by the Russian side.

Shoigu also discussed Ukraine on Sunday with Pentagon chief Lloyd Austin in their second phone call since Friday, however the Russian side did not mention the alleged "dirty bomb" provocation in its statement.