The Black Crowes, on tour in support of their March 2008 release, "Warpaint," have cancelled a pair of weekend shows: September 13 at The Joint in Las Vegas, NV, and September 14 at the Civic Auditorium in Santa Cruz, CA.

According to a post on the band's Web site, the concert cancellations are due to an unexpected illness within the band.

While the Las Vegas show will be rescheduled, the Santa Cruz show will not. Tickets for the original Las Vegas show will be honored for the rescheduled date, to be announced in the near future. Ticket refunds for the Santa Cruz show will be available at the point of purchase.

“We sincerely apologize for any inconvenience this unfortunate situation may have caused,” the Crowes said in a statement.

The blues rockers' Euphoria or Bust Tour, which kicked off in March, continues through December 20 with a five-night residency at The Fillmore in San Francisco, CA, on December 15-17 and 19-20.