An opposition leader in Belarus has gone on trial in connection with mass protests that followed the disputed presidential election in March.
Mr Kozulin was leading protesters on a march when he was arrested
Defeated candidate Alexander Kozulin denies hooliganism and inciting mass disorder, Belapan news agency said.
He was held after police broke up a protest march he led shortly after the 19 March poll in the capital, Minsk.
Belarus' authoritarian leader Alexander Lukashenko was re-elected in the poll, denounced by the West as fraudulent.
Western governments imposed sanctions on President Lukashenko and his top officials soon after the election.
Reporters and some of Mr Kozulin's supporters were denied entry to the court in Minsk, although observers from the European Union were allowed in.
If convicted, Mr Kozulin faces up to six years in prison.