A prominent Russian opposition figure says he was threatened by a group of men who then attacked him with a cake while he was dining at a restaurant in Moscow.

Mikhail Kasyanov said he was sitting in a central Moscow restaurant Tuesday night when around 10 men of "non-Slavic appearance" entered, threatened him and rammed a cake into his face, according to Russia's Interfax news agency.

A staunch critic of Russian President Vladimir Putin and the leader of the opposition Parnas party, Kasyanov said he filed a complaint with the police, concerned that the run-in had darker implications.

The incident came several days after Ramzan Kadyrov, the leader of Russia's Chechnya republic, posted a threatening video on Instagram that shows Kasyanov in the crosshairs of a sniper rifle.

The Kremlin on Wednesday called the cake attack an act of "hooliganism" and rebuffed the idea that it was related to Chechnya's leadership.