Sting [ tickets ], who is in the midst of the North American leg of a lengthy world tour, has canceled three performances due to an undisclosed illness, and has postponed a fourth date.

The singer-songwriter called of his planned weekend shows in San Diego (2/13) and Phoenix (2/14), as well as Tuesday's (2/17) show in Oakland, CA. Ticket-holders can obtain refunds at the point of purchase, according to a statement posted on Sting's official website.

Sting's Feb. 15 show at the Hard Rock Hotel-Casino's The Joint in Las Vegas has been postponed to Feb. 20; tickets for the Feb. 15 show will be honored on the new date.

Sting is touring the North American theater circuit behind his latest album, "Sacred Love." The outing opened in late January, and dates are set through mid-March.

"Sacred Love," Sting's 10th album, arrived in stores last September. The collection, which is the follow-up to 1999's "Brand New Day," features guest appearances from Vincente Amigo, Anoushaka Shankar and Mary J. Blige.