Hundreds of people, angered by last week's parliamentary election, joined a protest in central Moscow on Saturday, holding posters carrying slogans such as "bring back the elections".
The protest was organised by several politicians, most of them Communists, saying they were cheated of victory by an online voting system and calling for the system to be scrapped.
"I came here today to express my will that we have once again been deceived," said a woman at the protest.
Russian police detained opposition activists on Friday and warned they would break up any illegal rallies this weekend.
However, no detentions were seen at the protest on Saturday
About 400 hundred people, including journalists, joined the protest, the Interfax news agency quoted Moscow police as saying.
A Reuters witness estimated the number of people at the protest at around 1,500.
The final election results were released on Friday and handed the ruling United Russia party that backs President Vladimir Putin 324 of the State Duma's 450 seats.
The Kremlin has said it wants electronic voting, which was used in Moscow for last week's election as well as several other regions, to be rolled out nationwide in future votes.
The election was held in accordance with the law, the RIA news agency quoted Putin as saying at a meeting with leaders of the Duma parties on Saturday.
(Reporting by Polina Devitt; editing by Jason Neely)
