Cambodia's Senate has approved tight restrictions on non-governmental organizations, rejecting appeals from rights groups that say the law could be used for political repression.

About 400 protesters gathered peacefully outside Parliament during the vote on the bill Friday.

Senators from the opposition Cambodia National Rescue Party boycotted the session in protest against the bill, as the party's lawmakers in the lower house did last week when the bill passed there.

All 44 Senators present from the ruling Cambodian People's Party approved the bill, which now faces the formalities of a legal review and signing by King Norodom Sihamoni.

A major criticism is that the law would allow the authorities to de-register associations that they consider not to be politically neutral.