Harare, Zimbabwe (CNN) Oliver Mtukudzi, one of Zimbabwe's most celebrated musicians, died Wednesday of an undisclosed ailment, a former colleague has said.

"He has rested. He had been in and out of the hospital since last year when he developed a heart problem," Clive Mukundu, a music producer who worked with Mtukudzi, told CNN outside the private medical center where the 66-year-old musician was being treated.

A spokeswoman for his record label also confirmed the news to CNN.

Caroline Morabe said: "I can confirm that Oliver Mtukudzi has passed on. The family will release an official statement with more details later today."

The soft-spoken star missed a prize-giving ceremony Tuesday, raising speculation that his illness had taken a toll.

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