December 6, 2006 -- BRITNEY Spears' wild and crazy nights with new pals Paris Hilton and Brandon "Greasy Bear" Davis have caught the eye not only of her concerned fans and the public - but also of the Los Angeles Department of Children & Family Services.

A source close to the singer said, "The department has been calling Britney trying to set up a meeting with her, so they can check on [Spears' baby sons Sean Preston and Jaden James]. The calls started after this recent bout of bizarre public behavior."

But they are not the only ones worried about Spears.

Her family is aghast at her all-night partying with Hilton and Davis and were mortified when, on four separate occasions, Spears was shot by paparazzi not wearing any underwear.

The family source said her mother, Lynne, "is very disturbed and has been trying to get a hold of Britney, but she can't. Lynne, Britney's brother, Brian, and her dad, Jamie, are very upset and are trying to stage an intervention with [Spears' manager] Larry Rudolph's help."

A rep for the Department of Children & Family Services in L.A. didn't return calls.

But it wouldn't be the first time the family service agency's social workers paid a visit to Spears. On April 8, representatives for the department, along with the L.A. County Sheriff's office, went to the Malibu home Spears shared at the time with hubby Kevin Federline after Sean Preston fell from a high chair and hit his head while he was under the care of a nanny.

Another friend of Spears said it is possible the department is now merely following up on that original visit. But the Spears household has probably become even less stable since April.

Three different times, Britney has checked into L.A. hotels like the Viceroy with Hilton, rather than go home to her sons, who are presumably being watched by her mother.

Us Weekly reports that father Jamie recently had a stern talk with his Britney. The magazine notes, "He was not happy with her antics . . . He told her that she's a grown woman and needs to act like one, and she's been making bad decisions."