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ET has learned that R. Kelly had to cancel scheduled appearances on the Today show and Late Night with Jimmy Fallon after falling ill this morning.

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A rep for the multi-platinum singer tells ET that R. Kelly was on his way to New York to promote his memoir SoulaCoaster: The Diary of Me when he had to return to Chicago for medical treatment.

"Initial indications are that he is suffering from complications from surgery he had last year to treat an abscess on his vocal cords," the rep says. "It is unclear how long Kelly may be sidelined."

The R&B king's latest album, Write Me Back, dropped on Tuesday and his book releases Thursday.