Russian authorities have detained around 30 people outside the Moscow mayor's offices for holding an unsanctioned rally, according to RFE/RL's Russian Service.
The detainees included two prominent activists, opposition Left Front member Sergei Udaltsov and For Human Rights movement leader Lev Ponomarev.
The demonstrators were said to be demanding a return from the current system for naming mayors and regional governors, in which the president nominates such officials, to popular elections for such posts.
But police moved quickly after the participants gathered.
The rally appeared to have attracted several hundred people.
Udoltsov congratulated the Russian capital on its "release" from what he called the "Luzhkov occupation," a reference to President Dmitry Medvedev's recent sacking of the powerful Yury Luzhkov, who had exerted tight control over city affairs for 18 years.