Whitney Houston in rehab for drugs, alcohol

Whitney Houston, who has publicly battled varying degrees of drug addiction for years, has entered rehab.

"Whitney Houston is currently in an outpatient rehab program for drug and alcohol treatment," her representative said in a statement. "Whitney voluntarily entered the program to support her long-standing recovery process."

The six-time Grammy Award-winning pop/R&B singer, who has sold more than 170 million albums, singles and videos, enrolled in the program about 11 days ago, said TMZ.com, which first reported the story.

The rehab program, whose name and location was not revealed, allows the "I Will Always Love You" singer to venture out in public, provided Houston wears a monitor, TMZ said. Last Thursday, Houston and singer Chaka Khan made a guest appearance at Prince's concert at The Forum in Los Angeles, duetting to Khan's "Tell Me Something Good" while Prince played bass.

In 2009, after releasing a comeback album, she declared herself healthy and clean. However, Houston canceled some dates on her 2010 tour due to illness and received negative reviews because of the quality of her voice and performance. Earlier this year, she gave an uneven performance in tribute to cousin Dionne Warwick at music mogul Clive Davis' annual pre-Grammy gala.