Britney Spears' stay in a psychiatric ward was extended for two weeks under a section in state law that allows patients to be kept for medical treatment if they are found to be gravely disabled or a danger to themselves or others, a person close to the pop star told The Associated Press.

Spears was to be released Sunday from UCLA Medical Center's psychiatric ward after undergoing a 72-hour mental evaluation.

But doctors and a ward medical officer cited California law to keep her longer, said the person close to Spears, who requested anonymity.

Spears' detainment made it unlikely she would appear at a scheduled Monday morning hearing over custody of her children, 1-year-old Jayden James and 2-year-old Sean Preston.

Spears, 26, lost custody of the boys to ex-husband Kevin Federline following an incident last month when she refused to return the children after a visit.

Spears was briefly hospitalized at the time. On Thursday, she was again hospitalized.

On Friday, Court Commissioner Reva Goetz ruled that Spears needed someone else to take over her personal and financial affairs.

Spears' father, James, and her attorney, Andrew Wallet, were granted conservatorship, but a court hearing was scheduled Monday afternoon to review the matter.

A UCLA Medical Center spokesman did not immediately return a phone message Sunday seeking comment. Calls to Wallet and attorney Sorrell Trope also were not returned.

Spears' erratic behavior since she filed for divorce in November 2006 has included appearing in short skirts without underwear, shaving her head, abandoning a car in traffic when it had a flat tire, and recently, holding her dog and sobbing on a sidewalk.