Cambodia's ruling party has filed a complaint charging a prominent social commentator with criminal defamation for saying the party was manipulating a sex scandal involving an opposition leader.

The complaint filed Monday by the spokesman of the Cambodian People's Party charged that Ou Virak, who heads the Future Forum think tank, made a false allegation that damaged the party's honor.

Virak's comments several days ago to the U.S.-backed Radio Free Asia referred to a complicated series of events that began two months ago when taped phone calls of Kem Sokha, deputy leader of the opposition Cambodian National Rescue Party, speaking with at least two women were posted on the Internet. Their contents seemed to indicate Sokha was having an adulterous affair.