The actor who played the nerdy Screech in the US sitcom Saved by the Bell has surfaced as the star of his own sex tape.

According to US media reports, Dustin Diamond features in a 40-minute three-way video with two women.

Diamond, 29, is a black belt in karate and became well-known as the comic relief in the show, which ran from 1989 to 1993.

TMZ.com says Dustin Diamond called a Tampa, Florida radio station and didn't deny he was part of the video.

"I've had a lot of fun with video in the past," he told the station.

Hi agent told the New York Daily News that Diamond was trying to escape the Screech typecast.

"So this may help get more bookings."

Ironically, he is the second former star of the show to be seen nude.

In 1996, co-star Elizabeth Berkley appeared in Show Girls, a movie about strippers.