London, Jan 4 (ANI): Troubled pop star Britney Spears was taken to hospital to for an alcohol or drugs test, as well as a psychological evaluation, after police were called to her home following a row over her rights to see her children.

According to TMZ.com, the singer refused to turn over her two children to ex-husband Kevin Federline, and authorities discovered her under the influence of an unidentified substance.

According to a police source, the Los Angeles Police Department was called to Spears' house over a "family custodial dispute that we are trying to resolve peacefully by court order."

Spears appeared to be conscious while she was being wheeled out of her Los Angeles house on Jan 3, about three hours after police and ambulances arrived there.

The singer has been taken Cedars Senai Medical Center in Los Angeles.

The spokesman said that the singer's two sons, Sean Preston and Jayden James have been returned to their father, Kevin Federline, who has primary legal custody of the kids.

Spears has been in a bitter battle with Federline over custody of their two sons. (ANI)