Police detained almost 200 protestors at unsanctioned opposition rallies in Moscow and St. Petersburg on Tuesday, RIA Novosti reported.
In Moscow, police arrested some 70 people, including the Other Russia opposition party leader Eduard Limonov, Left Front opposition movement leader Konstantin Kosyakin and co-chairman of the Solidarity opposition movement Boris Nemtsov.
Police in St. Petersburg detained 90 protesters, including Olga Kurnosova, leader of the United Civil Front opposition movement.
Russian opposition groups rally on Triumfalnaya Square on the last day of each month that has 31 days in defense of their right to freedom of assembly, as enshrined in Article 31 of the Russian Constitution.
The Triumfalnaya Square rally was not sanctioned by the authorities, and police have also arrested a number of demonstrators, a RIA Novosti correspondent reported from the scene.
Kosyakin and Limonov have been released, but will have to appear in court on September 9.
A spokesman for the Moscow police department, said about 400 people had gathered for the rally in the capital, including 300 journalists.
The elderly chair of the Moscow Helsinki human rights group, Lyudmila Alexeyeva, said she left Triumfalnaya Square as the area was too crowded due to the square's reconstruction. The Moscow government closed the area in mid-August, citing plans to build an underground car park there.
"There was a very narrow space left, where it was almost impossible to stand. It was jammed, so I left the square almost immediately. Now I am following the news on the radio," she said.