Florence Welch has revealed she underwent life-saving surgery that forced her to cancel shows this past week.

On Sunday, the Florence + the Machine singer took to Instagram to apologize to fans about cancellations at Zurich Openair and Rock en Seine festivals in Europe.

"I'm so sorry that I had to cancel the last couple shows," Welch wrote. "I had to have emergency surgery for reasons I don’t really feel strong enough to go into yet, but it saved my life."

She continued by saying that she'll return to the stage Sept. 1 for a performance at Meo Kalorama festival in Lisbon, before closing out her Dance Fever tour Sept. 2 in Malaga, Spain. "Dance Fever," released last summer, is the fifth album from indie-rock band Florence + the Machine.

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"Suffice to say I wish the songs were less accurate in their predictions," Welch said. "But creativity is a way of coping, mythology is (a) way of making sense. And the dark fairytale of 'Dance Fever,' with all its strange prophecies, will provide me with much-needed strength and catharsis right now."

Welch, 36, previously postponed dates on the band's U.K. tour last November after she learned she was performing on a broken foot. "My feet are fine," she said in Sunday's Instagram post, but did not disclose any more specifics about her recent surgery.

Florence + the Machine is a seven-time Grammy-nominated group, best known for hits including "Dog Days Are Over," "Shake It Out" and "What Kind of Man." Welch also wrote the music and lyrics for an upcoming musical based on "The Great Gatsby," premiering in Cambridge, Massachusetts, next year.