Protesters against Russian President-elect Vladimir Putin have clashed with police in the capital Moscow, ahead of Mr Putin's inauguration on Monday for a third term.
The protest was peaceful until a small group of demonstrators tried to break through the lines of riot police.
Reports say opposition activists Alexei Navalny, Sergei Udaltsov and Boris Nemtsov have all been detained.
A rival demonstration in support of Mr Putin has also been taking place.
Organisers said about 20,000 people took part in the opposition march - to an island close to the Kremlin - although police put the figure at about 8,000.
Police have been blocking the protesters from crossing a bridge over the Moscow River.
Clashes broke out when more people crowded towards the bridge and riot police wielding batons pushed demonstrators back towards the rally site, witnesses said.
The BBC's Steve Rosenberg, who is at the opposition march, says protesters launched a sit-in by the police lines. Read More