Suffering from acute laryngitis, rocker Avril Lavigne has postponed six dates on her U.S. "Best Damn Tour."

She had already canceled shows in Phoenix and San Diego this week.

"My sincerest apologies to all of my fans," she said in a statement. "My intention was to complete the rest of the tour, but tonight at sound check in Anaheim, [Ca.], I realized this wasn't possible.

"Even though I have been resting my voice for days," she continued, "when I tried to sing nothing came out."

Refunds will be available at point of purchase on Monday.

Postponed dates are as follows:

05/03/08 Anaheim, CA Honda Center
05/04/08 Universal City, CA Gibson Amph. At Univ. CityWalk
05/06/08 Santa Barbara, CA Santa Barbara Bowl
05/07/08 San Jose, CA HP Pavilion At San Jose
05/09/08 Spokane, WA Spokane Arena
05/10/08 Everett, WA Comcast Arena / Everett Events Ctr.