Al-Jazeera correspondent in the Russian capital said that security forces broke up on Saturday a demonstration of the opposition in central Moscow, and arrested dozens of demonstrators who came out in protest against what they describe as the exclusion of candidates for local elections.
Independent police watchdog OVD-Info said police detained six hundred protesters.
For weeks, the opposition has been protesting against the forced removal of its candidates from local elections scheduled for September 8, with increasing pressure and threats from the authorities.
Saturday's protest comes despite mounting pressure from authorities that arrested nearly 1,400 people last week and launched a criminal investigation into the protest.
The security forces arrested the lawyer and opposition Lobov Sobol from a taxi while heading to participate in the demonstration.
Sobol is the last of the deported candidates arrested by security forces for calling unlicensed demonstrations and has been on an open hunger strike for days in protest at her exclusion from the elections and the arrest of activists and opposition leaders.
"The electoral commission is not doing its job, and the courts are not doing their job," the attorney said on the eve of her arrest.
"The authorities are doing everything they can to intimidate the opposition, and to ensure that people do not take to the streets to demonstrate peacefully."
On the other hand, OVD-Info said that among the detainees were six journalists during the demonstration.
As for the main opposition of the Kremlin, Alexei Navalni, the judiciary announced on Saturday the opening of a "money laundering" investigation against him.
According to investigators, people linked to the anti-corruption fund received amounts amounting to one billion rubles (13.8 million euros) illegally. They then "launder" those funds through several bank accounts before transferring them to the accounts of the Nafalini organization.
Navalni and other leaders of the protest movement say corruption is rampant in the capital. The opposition is currently in prison, and his loyalists are said to have been poisoned recently.