LOS ANGELES (Reuters) - A court commissioner has ordered Britney Spears to undergo random drug testing and hire a parenting coach to help the pop singer raise her children with ex-husband Kevin Federline, court papers showed on Tuesday.

The documents, which were posted on celebrity news site TMZ.com, result from a Monday hearing in the bitter custody battle between Spears and Federline over their two sons -- Sean Preston, 2, and Jayden James, 1.

"Based on the evidence presented, the court finds that there is habitual, frequent and continuous use of controlled substances and alcohol by the petitioner," who is Spears, Superior Court Commissioner Scott Gordon wrote in his ruling.

Federline had been asking for increased custody, but Gordon maintained a 50/50 joint arrangement.

Gordon ordered both Spears, 25, and Federline, 29, to complete a "parenting without conflict" program, and said each must refrain from making derogatory remarks about the other.

But he saved his most stringent requirements for Spears, who in recent months has exhibited odd behavior after completing a rehab program in March.

Spears has shaved her head bald, attacked paparazzi, fired staff, and stripped down to underwear for an impromptu ocean swim in front of photographers, among many incidents.

In July she was derided for lip-syncing songs while performing at Southern California nightclubs, and earlier this month she earned scorn at MTV's Video Music Awards dressing as a stripper and miming a new song, "Gimme More."

Gordon ordered Spears to undergo testing for drugs and alcohol twice per week on random dates and times.

She must meet with a counselor at least once a week to address parenting issues and work with a parenting coach at least eight hours a week in at least two sessions per week.