Backstreet Boy A.J. McLean checks into rehab

Backstreet Boy A.J. McLean has checked himself into rehab, though the singer vows it won't interfere with his band's planned summer tour with New Kids on the Block.

"For personal reasons, I've checked myself into a rehab clinic," McLean, 33, said in a statement Thursday. "With 2011 being a busy year for Backstreet, I want to be healthy and perform & sing for people at my very best and happiest. None of this will affect our current tour plans and I look forward to seeing everyone really soon! Thank you for all of your support and respecting my family and friends privacy during this time."

He did not specify where he was seeking treatment, or for what duration. McLean, an original member of the vocal quintet formed in 1993, has long battled addiction, entering rehab in 2001 and 2002 for both alcohol and drug abuse. He was reportedly six years sober in 2008, but witnesses at a club in January 2009 said he was drinking heavily and stumbling onto the street, TMZ.com reported at the time.

The site Thursday said a source told it that McLean has been "out of control" for the past few months because of his substance abuse, and appeared to be drunk last month during a Backstreet Boys cruise.

On Jan. 9 and 10, McLean posted references to a possible upcoming stay in rehab on Twitter: "I start my sober journey tomm! . . . This is gonna be an amazing year for me and all around me! I love u all and appreciate all the love and support. See u on the other side!"