The final six stops on the European leg of the Ozzfest tour have been canceled, according to tour participant Tool's official Web site.

The final six stops on the European leg of the Ozzfest tour have been canceled, according to tour participant Tool's official Web site. No explanation for the cancellation of shows in Zurich, Copenhagen, Stockholm, Helsinki, St. Petersburg, and Moscow has been given.

"Ozzfest has cancelled all the remaining European shows, starting from Friday 08 June to the end of the tour," the site reads. "Tool is coming home and will not play any more shows in Europe. The band sends their apologies to the disappointed fans."

Rumors abound that an unspecified illness suffered by Ozzy Osbourne guitarist and Black Label Society frontman Zakk Wylde is the reason for tour's abrupt end. Fan site Black Label Society.net reports that Wylde has returned to the U.S. for treatment of the mystery ailment.

The tour schedule on Wylde's official site reflects the cancellation of the dates, but offers no explanation. Tour organizer Sharon Osbourne Management and a spokesperson for Tool were not available for comment at deadline, and the official Ozzfest Web site has not been updated with any information about the schedule's change.

The U.S. leg of the Ozzfest tour is due to kick off July 6 in Bristow, Va., and play 31 dates through Sept. 8 in Dallas. As previously reported, the scheduled main stage lineup will feature Ozzy Osbourne, System Of A Down, P.O.D., Rob Zombie, Drowning Pool, Adema, and Zakk Wylde's Black Label Society.

Here are the canceled European Ozzfest dates:

June 8: Zurich (Hallenstadion)
June 10: Copenhagen (Valby Hallen)
June 11: Stockholm (Globen)
June 13: Helsinki (Hartwell Arena)
June 15: St. Petersburg, Russia (New Arena)
June 16 Moscow (Tushino Field)

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