Russian opposition leaders led a rally of several thousand people in Moscow on Saturday, protesting against the city election commission's decision to keep opposition candidates off the ballot in a local election.
About 30 candidates have been barred from running with authorities saying they failed to gather 3,000 signatures - the minimum required for a candidate to be allowed to run.
The barred candidates argue they have secured the appropriate number of signatures and are being barred from the poll because they pose a threat to Russian President Vladimir Putin's preferred candidates.
Russia's most prominent opposition leader Alexei Navalny issued an ultimatum to the city election commission: either they register all withdrawn candidates by next Saturday or the opposition would gather for an open-ended protest in front of the city hall.
Demonstrators chanted "let them run."
Other opposition figures Dmitry Gudkov, Ilya Yashin, Lyubov Sobol were seen at the rally as well.
Sobol, one of the disqualified candidates, went on hunger strike and came to the stage supported by another barred candidate Ivan Zhdanov.
Saturday's protest was sanctioned by the city authorities and police made no effort to intervene.
Al least 38 protesters were detained last Sunday when the crowd marched to the commission's office and were going to stage a sit in overnight.