Ramzan Kadyrov, the hardline pro-Moscow head of Russia's Northern Caucasus Republic of Chechnya, says more than 50 suspected militants have been detained in the biggest sting operation of recent years.
Moscow has waged two wars against separatists in the predominantly Muslim region since the collapse of the Soviet Union in 1991. The region is now ruled by Kadyrov, a former rebel fighter now loyal to President Vladimir Putin.
Civil rights activists accuse Mr Kadyrov of arbitrary arrests of dissidents.
Mr Kadyrov said in a video on his Instagram account that a group directed by a Chechen-born militant based in Syria had been targeted.
"As of now, all the band-group was neutralised, more than 50 of its participants were delivered to police stations," Mr Kadyrov said.
Some Chechens are known to be fighting as committed jihadis on the side of the Islamic State group in Syria and Moscow fears they may return to attack Russia, something they have threatened to do.