Seventeen activists were arrested for protesting the detention of activists who had staged a picket outside the Duma, the lower house of parliament, outside a Department of Internal Affairs office in central Moscow.
In Voronezh, a further 11 party activists were detained for disturbing public order, local police said.
Thirty-five party activists are now being held in Moscow, a police spokesman said.
The activists were burning signal flares, and had attempted to dislodge signposts and flags, demanding the release of party supporters, he said.
The Voronezh activists "attempted to handcuff themselves to iron railings, and were shouting anti-government slogans," in protest against the devaluation of private savings in Russia in the 1990s, a police source said.
The National Bolsheviks, led by controversial novelist Eduard Limonov, claim a total of about 15,000 members, most aged under 18. Outspoken critics of the present government, they have been repeatedly denied official registration as a political party.
