Police, security officers and migration officials in a joint raid on Friday detained some 300 people, including 170 foreigners, in a praying room for Muslims in a non-residential building in the southeast of Moscow, Interfax reported.
Police confiscated reading materials from the scene, saying they would be examined for extremism.
About 50 of the detained people were registered as administrative offenders over violating either migration or trade rules, or not having identity papers.
The raid was carried out as part of preventive measures to protect citizens from terrorism and other crime, police said.
(MT)