Lady Gaga was groped by fans as she crowd surfed half-naked at last weekend's Lollapalooza festival in Chicago.

The US singer jumped into the audience during a performance from her tour support and close friends, Semi Precious Weapons.

In a video of the incident, various fans can be seen grabbing parts of the singer's body, which was only covered by a precarious fishnet costume.

Lady Gaga spends just under a minute in the crowd, before returning to the stage and screaming something inaudible at the audience.

The singer went on to headline the Saturday night (August 7) of the festival, playing to a crowd of around 80,000 people on the main stage.

It was the most high-profile performance of the star's Monster Ball, and included renditions of the songs 'Bad Romance', 'Poker Face' and 'Just Dance'.

Other acts at Lollaplooza included Soundgarden, Arcade Fire, The Strokes and The Cribs.

(by Jason Gregory)