Dethroned former Miss California Carrie Prejean is at the centre of a new scandal following reports she's the star of a new sex tape.

The blonde beauty was stripped of her crown earlier this year after candid shots of her posing on a beach hit the Internet - a strict breach of the pageant's rules. Officials also took offence to her decisions to miss official engagements - an allegation she denied.

And now it appears Prejean, who hit the headlines when she questioned gay marriage at the Miss USA pageant, is caught up in another controversy.

A source who has seen the alleged sex tape tells TMZ.com Prejean appears to be "doing very graphic things to her body," adding no one else features on the tape.

The insider says Prejean claims she was 17 when the video was shot.