AceShowbiz -

Janet Jackson's comeback tour is not "Unbreakable". A few months after the R&B diva postponed a bunch of her North American shows, she has now scrapped all dates scheduled to take place in the U.K. and Europe.

The cancellations were revealed in an email sent by Ticketmaster to fans who had purchased tickets to the concerts. "It is not possible to confirm new date at the present time so we are refunding all ticket holders, you don't need to do a thing - you'll see a credit onto the card you used within 15 days," the email read.

Jackson's European tour dates, which were supposed to open on March 30 in Birmingham, the U.K., have all been removed from Ticketmaster's site. However, reason behind the cancellations is still unclear. The singer hasn't responded to request for comments.

Jackson's "Unbreakable" tour was launched last year following the release of her latest album of the same title. In October, she had to delay some dates to rest her vocal cords. In December, she was forced to postpone some other shows because she needed to undergo an emergency surgery.

"Please pray for me, my family and our entire company during this difficult time," she wrote at the time. "There will be no further comment. I love you all so much and am grateful for your understanding and your love. Gon' b alright."

Rumors then surfaced suggesting that her surgery was related to cancer. She has shot down the speculation, though.