Singer Robbie Williams Checks Into Rehab

British singer Robbie Williams has entered rehab, his rep confirms to PEOPLE.

"Robbie Williams has today been admitted into a treatment center in America for his dependency on prescription drugs," his spokeswoman, Bryony Watts, said in a statement.

The pop star, who turned 33 on Tuesday, currently lives in Los Angeles.

This is not his first time seeking help: In 1997 he checked into Clouds House Drink and Drugs Rehabilitation Clinic in Salisbury, England, for alcohol and drug addiction, and in October 2006 he was treated at London's The Priory for depression.

Williams is one of the UK's most successful solo artists, but his most recent album, Rudebox, which received mixed reviews, was not released in the U.S.