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The singer had the operation done at a Munich hospital, a band spokesperson said Friday.
Bono, 50, suffered an injury while practicing for the North American leg of the "360 Degree" world tour, due to start in Salt Lake City on June 3.
"Bono has today undergone emergency back surgery for an injury sustained during tour preparation training," his spokesperson said. "He was admitted to a specialist neuro surgery unit in a Munich hospital.
"Bono will spend the next few days there, before returning home to recuperate. Once his condition has been assessed further, a statement will be made regarding the impact on forthcoming tour dates."
After North America, the tour was to move to Turin, Italy, on August 6. It was not immediately clear how badly the injury would disrupt the group's tour.
The tour earned around $109 million in 2009, according to music journal Billboard, making it the world's most lucrative, and the publication also predicted it would end up being the highest-grossing tour in history.