The Basmanny district court ordered 20-year-old Valery Kostenok's detention until October 11 for throwing two plastic bottles at security forces during the demonstration, which was attended by several thousand Russians to protest against officials who didn't register several independent and opposition candidates on the ballot for a September 8 vote to the Moscow municipal legislature.

Kostenok has admitted his guilt.

Kostenok, who collected signatures as a volunteer in favor of Moscow City Duma candidate Kirill Goncharov, became the 14th person charged in the criminal investigation authorities opened on July 31 into the protest.

Also arrested and given a six-day prison sentence was Olga Guseva, a deputy of opposition leader Aleskei Navalny's campaign office, the rights group OVD-Info reported. She was charged in St. Petersburg, one of the 40 cities where rallies took place nationwide on August 10 for free and fair elections.

The rallies on August 10 rally were the fourth successive weekend demonstration in Russia.

The criminal probe into the July 27 demonstration was opened based on three articles of Russia's Criminal Code -- on organizing mass unrest, which carries a sentence of up to 15 years in prison; on participating in such unrest, which can be punished with up to eight years in prison; and on calling for unrest -- up to two years in prison.

The court rejected the request by Kostenok's lawyer that his client be placed under house arrest after investigators said he could go into hiding or establish contact with other defendants.

Kostenok’s lawyer, Gadzhi Aliyeva, said she would appeal the ruling.

With reporting by Current Time, Interfax, and TASS