Britney Spears was taken from her home by ambulance early today, police in Los Angeles said.
An officer, who requested anonymity because he was not authorised to speak on the matter, said the pop star was being taken to "get help" but did not say where the ambulance was taking her.
Earlier this month Spears was taken to a Los Angeles hospital by paramedics after police were called to her home because she refused to return her sons, Sean Preston, two, and one-year-old Jayden James to ex-husband Kevin Federline.
She since lost custody and visiting rights with the boys.
Police also went to the home on Monday night after someone reported a swarm of paparazzi trespassing in the singer's gated community. When officers arrived, they did not see anyone trespassing, police said, but tickets were issued for several illegally parked cars.
Spears has been in a highly public downward spiral since filing for divorce from Federline in November 2006.
Her bizarre antics include shaving her head, attacking a car with an umbrella and bringing along a paparazzo pal on trips to a courthouse in her custody case with Federline.