At least three Cambodian Buddhist monks were injured during a protest against Vietnam, which they accuse of suppressing the religious rights of its Cambodian minority.
A group of 40 monks tried to deliver a letter to the Vietnamese embassy calling for the release of three jailed Cambodian monks but were forced away from the compound by 200 riot police.
Scuffles ensued when they took their protest first to the royal palace, then the to the U.S. embassy.
Two other monks suffered injuries after pro-government protesters pelted them with bottles and rocks
The protest was timed five days ahead of a visit by the head of Vietnam's national assembly. Vietnam denies accusations by rights groups that it represses human rights and religious freedoms.