Bono thinks he is "overpaid".

The U2 rocker - who is worth an estimated £400 million - says he devotes so much of his time to charitable projects because he believes he has more money than he deserves to have.

Speaking at the launch of Nike's Lace Up. Save Lives campaign, which raises money for HIV charity (Red) with Chelsea soccer star Didier Drogba, he said: "These guys are very wealthy. I am very well paid, overpaid and even over-rewarded for what I do. But a lot of these soccer guys are giving something back and they don't need to do that."

Meanwhile, Bono admits he and his bandmates are "delighted and humbled" to have been asked to headline next year's Glastonbury Festival, which is celebrating its 40th anniversary.

He said: "Everyone in the band is very excited about it. I think it will just be about the music on that day, and that spirit that seems to take over everybody in that sacred ground.

"We'll certainly be well-rehearsed, we'll be coming straight from the North American tour."

U2's appearance at Glastonbury marks their first festival show in 25 years and it will be the first time the group have performed at the world famous music event.