Ten people were detained on Tuesday after a nationalist movement called for Russians to gather in downtown Manezh Square, a Moscow police spokesman said, RIA Novosti reported.
Earlier a police source said more than 50 people were arrested.
The previously unknown December 11 Movement, named in reference to last year's mass rioting by nationalists and football fans over the death of a Spartak supporter, had called for a "Russia for Russians" rally in the square today.
The source said earlier the leader of the outlawed Slavic Union nationalist movement, Dmitry Dyomushkin, was among those detained.
Russian Prosecutor General Yury Chaika said in an interview with the pro-Kremlin Rossiiskaya Gazeta newspaper that race hate charges were brought against 21 people who took part in the December 11 unrest.