Police have arrested hundreds of people in Moscow in an attempt to prevent gatherings of Russian nationalists and Caucasians which have sparked ethnic violence.
Some 7000 soccer fans and nationalists last week demonstrated near Red Square and attacked passers-by. More than 30 people were injured.
About 500 young people on Saturday marched in a park near the Ostankino television headquarters shouting slogans such as "Russia for the Russians".
Police said most were in their teens. Knives and stun guns were confiscated.
A similar crackdown was held on Wednesday, when about 800 Russian youths and migrants from the Caucasus and Central Asia were detained near the central Kievsky railway station.
Moscow's mayor issued an order on Friday putting more police on the streets.
Prime Minister Vladimir Putin said on Thursday that all forms of extremism must be prevented.