It was not immediately clear what may have led to the incident. Newspapers made a link to an incident earlier in the day when, during his band's set on the festival's second day, Haddon threw himself into the audience to crowd surf and injured a teenage girl, who had to be taken to hospital. Haddon immediately provided contact details in case the girl's family made a damages claim. She was later released from hospital and her condition was said to be not serious.

According to other reports, the band had recently severed links with a long-time collaborator, which had left Haddon depressed. Hasselt public prosecutor Marc Rubens, who happened to be at the festival as a spectator, said the death was being treated as a suicide.

The release of the band's first album in October will go ahead despite the singer's death, the record company said this week. The band, which was due to play concerts in Europe before embarking on a tour of Australia in September, have released three singles and made their name playing at Glastonbury and Bestival and supporting La Roux on its recent tour.

A statement on the Pukkelpop website said: "After performing with his band, singer Charles Haddon decided to take his own life. Our thoughts go out to his family and friends." Festival director Chokri Mahassine said the singer's death was "a severe personal blow" but defended his decision to let the three-day festival go ahead. About 65,000 people per day attended the event.

The death was the second to have marred what should have been a celebration, as Pukkelpop marked its 25th anniversary. On the first day of the festival, 19 August, 60-year-old American Michael Been collapsed and died of heart failure while working as sound technician for his son's band, Black Rebel Motorcycle Club. Been was himself a performer in the 1980s and '90s, as frontman of The Call.