NEW YORK - Amy Winehouse has put her North American tour on hold, raising more concerns about her health. "Due to the rigors involved in touring, Amy Winehouse has been advised to postpone her upcoming September U.S. and Canadian tour dates," the British singer's publicist, Tracy Miller, said in a statement Tuesday.

"Amy's European and U.K. tour dates in October and November remain in place. Plans are being made to reschedule her U.S. tour for early 2008. Until then, Amy has been ordered to rest and is working with medical professionals to address her health."

Last week, it was announced that the 23-year-old was canceling all her August performances due to "severe exhaustion." While British tabloids have claimed the retro-soul singer has been in rehab due to drug abuse, her spokeswoman has denied such claims.

Winehouse made her U.S. debut this year with the acclaimed album "Back to Black," but her celebrity has been fueled by her tabloid image as much as her talent. She's spoken openly about her past battles with drugs and her penchant for alcohol and marijuana, and her hit single "Rehab" is an autobiographical tale of her resistance to being pushed to go to rehab: "They tried to make me go to rehab, but I said no, no, no."

Winehouse was scheduled to appear at the MTV Video Music Awards on Sept. 9 in Las Vegas, but it is unclear if she will be on hand for the event.