The guitarist is thought to have fallen out of a tree while on holiday in Fiji.

"Excuse me, I fell off of my perch, " he said. "Sorry to disrupt everyone's plans . . . but now it's full steam ahead."

Several concerts have been rescheduled but ten dates are still postponed and two German concerts, in Nuremburg and Leipzig, have been cancelled.

Their UK dates in London, Glasgow, Sheffield and Cardiff in late August remain unchanged. The first performance will be at the San Siro stadium in Milan on 11 July, Richards suffered the head injury during a break in the tour schedule. He was originally thought to have sustained "mild concussion" but needed surgery several days later.