At least 3,500 people have been detained during a series of anti-war protests across Russia on Sunday, the Russian Ministry of Internal Affairs has said, according to Russian news agencies.
The rights groups OVD-info put the number of people arrested at 4,640 in 65 cities on Sunday.
It brings the number of demonstrators arrested since the start of the Russian military invasion to more than 13,000.
Numerous rallies have taken place across Russia since the beginning of the invasion, despite new laws being passed to crack down on protesters.
Russian state TV showed mass rallies held across the country in support of what Russia is still calling "the special military operation in Ukraine".
Motor rallies with flags flying from car windows and stickers saying ‘For Victory’ were held along the central streets of several cities.
People also laid flowers at memorials and sang war songs.