LOS ANGELES — Britney Spears’ continuing downward spiral took a devastating turn Monday when she was ordered to relinquish custody of her children by a judge who had cited her drug-and-alcohol-fueled lifestyle.

Superior Court Judge Scott M. Gordon ruled that her ex-husband Kevin Federline will take Sean Preston, 2, and Jayden James, 1, beginning Wednesday “until further order of the court.”

The order stemmed from an unspecified oral motion made by Federline’s lawyers and was handled in a closed-door hearing. The judge’s order did not state the reason for the change in custody and he ordered all transcripts of the proceedings sealed.

Last month, Gordon said Spears engaged in “habitual, frequent and continuous use of controlled substances and alcohol” and ordered her to undergo random drug and alcohol testing.

Spears also was previously ordered to meet weekly with a parenting coach who would report back to the court about her parenting skills. Both Spears and Federline must complete a “Parenting Without Conflict” class.

Spears, 25, and Federline, 29, were married in October 2004. She filed for divorce last November and it became official in July. The two have joint custody of their sons, but Federline is seeking a greater share of custody.

Since Spears became single, her troubles have played out in the tabloids. First she was photographed partying hard with Paris Hilton. Then Spears shaved her head, beat a car with an umbrella and ended up spending a month in rehab.

An MTV Video Music Awards performance last month meant to herald her comeback was universally panned. The following week, Spears’ management firm dropped her and her divorce lawyer resigned. She then was charged with misdemeanor counts of hit-and-run and driving without a valid license.