NEW YORK - U.K. pop singer Lily Allen has canceled most of her May-June U.S. tour because she is "tired," and believes her live show of late has been sub-par.

Allen revealed the news on her MySpace page, admitting that she's been "getting really drunk" recently, and has become "so nervous about doing bad shows."

She added, "I am not falling apart at the seems, I am not suffering with exhaustion, I am not pregnant, and I am not going to rehab. I will be here in America, promoting the album and also starting to write the second album, which I am beyond excited about."

The affected shows -- about 10 in all -- will be rescheduled in the fall, a spokesperson said. She will play the upcoming Coachella (April 29) and Bonnaroo (June 15) music festivals, among several others.

The singer is scheduled to perform Tuesday on "The Tonight Show with Jay Leno," and Wednesday on "The Ellen DeGeneres Show." She is touring to promote her debut album "Alright, Still," and the gleeful post-breakup single "Smile"