More than 1,200 people have been arrested in Russia in raids a day after major riots in southern Moscow.
The “pre-emptive raid” targeted migrants, Russian news agencies said.
The protests were sparked by the death of a young ethnic Russian allegedly stabbed to death on Thursday by a Muslim migrant from the North Caucasus.
Demonstrators stormed a shopping centre, smashing windows, and then overran a wholesale vegetable market searching for migrant workers.
Ethnic Russian Yegor Shcherbakov, 25, was killed on Thursday in front of his girlfriend.
Police have released a security camera photo of the suspect, but have not identified him.
Media said the image suggested the man was of “non-Slavic appearance”, leading nationalists to conclude the killer was a Muslim migrant from the Russian North Caucasus.
The issue of immigration and internal migration was one of the main issues in Moscow’s recent mayoral election won by Sergei Sobyanin.