Russia's top domestic security agency says it has detained a group of suspects accused of planning firebomb attacks on official buildings.

The Federal Security Service, or FSB, said Friday the suspects detained in the Moscow region were planning to throw firebombs at administrative buildings and attack police over the weekend in order to provoke mass riots.

It said the suspects belonged to the Artpodgotovka group founded by opposition activist Vyacheslav Maltsev. Maltsev said Russia is up for a revolution this weekend just as the nation prepares to mark the centennial of the 1917 Bolshevik revolution on Nov. 7.

Maltsev, a former regional legislator, unsuccessfully ran for the federal parliament in 2016. He left Russia in the summer and in October was arrested in absentia on extremist charges.