Police officers stand guard on the platform of a metro station in Moscow, capital of Russia, on April 3, 2017. (Xinhua/Oleg Brusnikin)

MOSCOW, Nov. 3 (Xinhua) -- Members of an extremist organization who were planning a series of firebomb attacks to trigger riots for the coming weekend have been detained in the Moscow Region, the Russian Federal Security Service (FSB) said Friday.

The detainees are members of Artpodgotovka (Artillery Bombardment), a society founded by Vyacheslav Maltsev, a Russian politician and critic of President Vladimir Putin, who is accused of predicting or trying to mastermind a "revolution" in Russia on Nov. 5.

The detainees, whose names and number were not disclosed immediately, were planning to attack administrative buildings and police, an FSB statement said.

Fifteen petrol bombs, known as Molotov cocktails, were seized during the operation, the FSB said.

Maltsev, who faces a criminal case, was said to have fled Russia and his whereabouts remain unknown, according to an Interfax report.

Law enforcement bodies have suppressed the activities of Artpodgotovka cells in five cities in central and southern Russia and in Siberia, the FSB said.