Robin Williams is interviewed at the premiere of 'RV' at the Mann Village theatre in Los Angeles April 23, 2006. Williams has entered treatment for alcohol abuse after being sober for 20 years, his publicist said on Wednesday. (Mario Anzuoni/Reuters)

Comedian and Oscar-winning actor Robin Williams has entered treatment for alcohol abuse after being sober for 20 years, his publicist said on Wednesday.

Williams, 55, "found himself drinking again" after two decades of sobriety and "has decided to take proactive measures to deal with this for his own well-being and the well-being of his family," spokeswoman Mara Buxbaum said in a statement.

"He asks that you respect his and his family's privacy during this time," she said, adding, "He looks forward to returning to work this fall to support his upcoming film releases."

Besides "The Night Listener," which opened last week and stars Williams as a radio host who becomes involved with a young listener who claims to be a child-abuse victim, the actor has three more movies set to hit theaters this year.

He plays another talk show host who runs for president in the upcoming film "Man of the Year," due out in October, supplies the voice of a penguin in the polar cartoon "Happy Feet," set for November, and co-stars with

Ben Stiller and Owen Williams in the comedy "Night at the Museum," due in December.

Williams, who once incorporated jokes about his bouts with excessive drinking into his stand-up comedy routines, became a household name as the star of the 1970s sitcom "Mork & Mindy" and went on to a successful film career.

He received Academy Award nominations for his dramatic lead roles in "Good Morning, Vietnam," "Dead Poets Society" and "The Fisher King" and clinched the Oscar as best supporting actor in "Good Will Hunting."