But government supporters, many possibly plainclothes police officers, moved in, beating demonstrators, opposition leaders said.

They also demanded the release of 46 people detained by the police and penalties for policemen who beat demonstrators.

A genuine opposition group called the Alliance for Change has recently staged nightly street rallies, though the police have beaten demonstrators several times.

"Beating peaceful demonstrators is inconsistent with that image and violates its obligations under human rights law."

The police here have beaten demonstrators in the past, drawing international criticism for cruelty and disproportionate use of force.

The police were instructed not to beat demonstrators or opposition supporters.

Current military rules allow soldiers to beat violent demonstrators but they are supposed to stop when the suspects submit to arrest.

Security forces beat demonstrators, fired tear gas and drenched the crowd.

Their troops beat demonstrators protesting election fraud, and some have ties to a group that has attacked religious minorities.

The police responded with tear gas and by beating demonstrators with nightsticks.