Jimmy Carter has been hospitalized, RadarOnline.com has learned. A rep for the Carter Center says he currently is "resting comfortably."

The former president was on a flight to Cleveland when he began suffering from “unknown health issues” according to reports.

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Carter, who turns 86 on Friday, was headed to a book signing event at Joseph-Beth Booksellers in Cleveland for his new tome White House Diary.

According to CBS News, Carter was taken off the plane by rescue crews and rushed to the hospital.

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Jackie Mayo, a spokeswoman for Cleveland Hopkins International Airport, says Carter was on a Delta flight late Tuesday morning before being taken to Metro Health Hospital. She had no further information on his symptoms.

"While on a flight to Cleveland, former U.S. President Jimmy Carter developed an upset stomach, and, upon arrival, was taken to Metro Health Hospital for observation," Deanna Congileo, spokeswoman for the Carter Center, said. "He is resting comfortably and is expected to resume his book tour this week."

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