A local Jehovah’s Witnesses leader was reportedly detained in the Siberian city of Novosibirsk amid an ongoing crackdown on the religious group that has been labeled as extremist in Russia.

Russia outlawed Jehovah’s Witnesses in 2017, equating the country’s estimated 175,000 adherents to members of a terrorist group, making it illegal for them to congregate or distribute literature. Last month, investigators claimed to have seized explosives from members of the religious group in the Volga region of Kirov — a claim that a spokesperson for the group denied.