Russian opposition leader Alexei Navalny is ambushed by police in Moscow just after breaking house arrest.
He is detained and then driven back home, local media reported.
100 anti-government protesters were also arrested.
Demonstrators had been rallying for freedom of expression.
(SOUNDBITE) (Russian) MOSCOW RESIDENT, ALLA, SAYING:
"I came here first of all because I am against any repression, against politically motivated cases and prosecution for views. I think every person has the right to express his opinion."
Navalny was sentenced to house arrest earlier in the day for embezzlement. His brother was sentenced to three and a half years in a case seen as part of a campaign to stifle dissent.
Government opponents say jailing Navalny, who led protests against President Vladimir Putin three years ago, could trigger a new wave of protest.
