Aerosmith have canceled a handful of dates while singer Steven Tyler recovers from an undisclosed illness. Tyler, who had been touring South America with the band, flew back to the U.S. last night.

The canceled dates set for later this month and in early October were to be the final four stops on the band's Aero-Vederci Tour. "Steven is expected to make a full recovery," according to statements posted to the social media accounts of Aerosmith and the singer. "With proper rest and treatment, he will be back on his feet soon, rocking the world."

In separate comments, Tyler apologized to fans. "To everybody in South America – Brazil, Chile, Argentina and Mexico – I'm very sorry and feel like I've let you down," he wrote on Facebook. "I won't be able to continue the last four shows of this tour. I flew back to the U.S. on doctor's orders last night after the show in São Paulo."

Thousands of fans responded to the news, wishing him well. But while Tyler has not disclosed the nature of his illness, he said he will be back.

"Please not to worry," Tyler continued. "I am not in a life-threatening condition, but I need to deal with this right away and get some rest and medical care immediately in order to sustain and maintain my future performances. I promise I'll be back. Unfortunately, health does not wait and it's something even I can't schedule around our shows. As they say, 'We humans make plans, and God laughs.' I love you all and will be back with you soon."

The 69-year-old Tyler isn't the first Aerosmith member to suffer health problems on a recent tour. Last year, guitarist Joe Perry collapsed onstage while on the road with Hollywood Vampires, though his bandmates briefly continued the tour without him while he recovered.

Earlier this year, Aerosmith decided to postpone a North American tour in favor of working in the studio on new material.

Aerosmith Albums Ranked Worst to Best