Some viewers were outraged over Lambert's (left) performance

American Idol star Adam Lambert's performance at Sunday's American Music Awards has prompted more than 1,500 complaints by viewers.

During the closing act, the openly gay singer simulated sex on stage with a back-up dancer and kissed a male musician on the mouth.

Lambert told US network CNN that the kiss was "in the moment".

ABC said the number of complaints was "moderate". The show's producers have declined to comment.

Lambert, who performed his debut single For Your Entertainment, said that if people had been upset by his performance that it is a "form of discrimination and it's too bad".

He added: "I had fun, my dancers had fun, the audience that was in the Nokia [Theatre] had fun.

"Anybody else who was watching it and enjoying it, thank you for being entertained."

'Tasteless'

The Parents Television Council (PTC), a media pressure group which campaigns against "indecent" content on US television, posted a statement on its website calling the show "tasteless" and "vulgar".

President Timothy Winter said members were "outraged".

He added: "They just can't believe the nature of the content, the explicit nature, and how much graphic content there was."

Lambert's kiss recalled the MTV Video Music Awards moment in 2003 when Madonna and Britney Spears briefly kissed on stage.

And in 2004, Janet Jackson exposed her right breast during the Super Bowl half-time show.

The "wardrobe malfunction" prompted more than 500,000 complaints.