"The FSB identified and stopped the activities of a clandestine cell” of Daesh supporters, the Russian Federal Security Service (FSB) said in a statement on Friday, adding that they "planned to commit attacks on December 16."
The security service further said that the group planned "the killing of citizens" in crowded areas of Russia’s second city.
Russian forces arrested seven members of the cell during raids that took place on Wednesday and Thursday.
According to the statement, a "large number of explosives used to make homemade bombs, automatic rifles, munitions and extremist literature" were seized during the police operation.
FSB chief Alexander Bortnikov said on Tuesday that Russia was on alert for the possible return of Takfiri militants from Syria ahead of the FIFA World Cup and the presidential election in 2018.
Back in April, some 14 people were killed in an attack in Saint Petersburg.
Russia has been hit by a number of high-profile attacks by Daesh since the country became involved in the war on terror in Syria.
Intelligence agencies have managed to defuse several plots but Moscow and other cities still remain major targets for Daesh as the terrorist group has vowed to continue launching attacks in retaliation for Russia’s assistance to Syria, which has proved helpful in purging the Takfiri terrorist group and other militants from major Syrian cities.
Russia has defended its military campaign in Syria, saying it is also meant to prevent the return of thousands of its nationals believed to be operating along the ranks of Daesh in the Arab country.