U2 have completed ''70 per cent'' of their 14th studio album.

The Irish rockers recently released their 13th LP, 'Songs of Innocence', but bassist Adam Clayton has revealed the group are nearly ready to go on their next release, 'Songs of Experience', insisting it should be ''relatively easy'' to finish.

Speaking in the new issue of Q magazine, he said: ''I think we've probably got 70 per cent of the material that we think will go onto it.

''The 30 per cent that we're missing I think we'll be able to generate relatively easily.

''But the amount of energy it will take to refine the perspective of those songs is hard to predict.''

The band - also made up of Bono, The Edge and Larry Mullen, Jr. - caused controversy when they released 'Songs of Innocence' through Apple which saw it automatically land into the iTunes library of millions of people, but Adam admitted the group will be opting for a different delivery method next time.

He added: ''Y'know what, depending on how long it takes to be completed, there may be a whole new delivery method invented by then ... I think we just have to wait and see.

''There'll be a bit of water under the bridge before we get to that point. But yeah, I think it would be a bit predictable to do the same thing.

''And y'know, the law may have changed by then and we'll have to find some other way of doing it.''