Bono thinks music has ''gotten very girly''.

The 57-year-old U2 frontman - whose real name is Paul David Hewson - has had a career spanning almost 41 years with the band and although coming from a rock background, Bono believes men can now only express ''anger'' through hip-hop.

In an interview with Rolling Stone magazine, Bono said: ''I think music has gotten very girly. And there are some good things about that, but hip-hop is the only place for young male anger at the moment - and that's not good.

''When I was 16, I had a lot of anger in me. You need to find a place for it and for guitars, whether it is with a drum machine - I don't care.

''The moment something becomes preserved, it is f**king over. You might as well put it in formaldehyde.

''In the end, what is rock & roll? Rage is at the heart of it. Some great rock & roll tends to have that, which is why the Who were such a great band. Or Pearl Jam. Eddie has that rage.''

U2 have just dropped their latest album, 'Songs of Experience'.

But despite his years of experience, Bono still finds songwriting to be very ''demanding''.

He said: ''I gave myself to the singing in new ways, but there wasn't a lot of going out and discovering the places we were playing, the cities that we were playing, which I really love to do.

''Stepping inside the songs was more of an ordeal than I thought it would be. They are very demanding in terms of their emotional - what word am I looking for ... forthrightness.

''And then we were preparing for 'Songs of Experience'. All that promotion takes a lot more work than I remember, but if you believe in the songs, you have to defend and present them.''