Troubled pop star Britney Spears is being treated for postnatal depression at the luxury Malibu rehab centre she entered last week, the celebrity website TMZ.com has reported.

It said doctors believed that post-childbirth blues were the underlying reason for her substance abuse, though there is also a possibility she could be suffering from bipolar disorder.

The report said doctors believed that Spears was drinking to self-medicate her problem, which has been complicated by an intense feeling that she had lost control of her life.(DPA)