Russia on Friday summoned France's ambassador in Moscow and issued a formal complaint over his country's alleged "growing involvement" in the conflict in Ukraine.
The move comes just days after Moscow claimed -- without providing evidence -- that it had killed a group of French mercenaries in a strike on the northeastern town of Kharkiv.
"On 19 January, French Ambassador P Levy was summoned to the Russian Foreign Ministry and presented with evidence of Paris's growing involvement in the conflict over Ukraine," Russia's foreign ministry announced in a statement.
Moscow said dozens of fighters were killed in the late night attack Tuesday in Kharkiv, which Russian forces have been shelling since February 2022.
Kyiv said more than a dozen civilians were wounded in the attack and that residential buildings had been damaged.
France's foreign ministry on Thursday denied it had mercenaries in Ukraine, a spokesman dismissing the claim as "another clumsy Russian manipulation".
France has been one of Ukraine's staunchest allies since Russia's invasion, and President Emmanuel Macron this week announced Paris would send dozens of long-range missiles to Ukraine.