Spears must give 'working' number

Britney Spears divorced Kevin Federline in July

Britney Spears must provide a working telephone number so she can be reached for drug testing, a court has ruled.

Ex-husband Kevin Federline's lawyer told the court there had been 14 requests for drug testing and she failed to respond to eight of them.

Ms Spears' lawyer argued the singer had not responded within the ordered timeframe because she was sleeping.

Mr Federline was granted full custody of sons Sean Preston, aged two, and one-year-old Jayden James in October.

"There needs to be one number that the testing facility calls that she responds to," Superior Court Commissioner Scott Gordon said.

He added that she could change phone number, as long as everyone involved was notified.

'Perfectly clear'

Mr Gordon said the process should be perfectly clear for Ms Spears.

"You get a call, answer the call, set up a meeting, get the test," he said.

Mr Federline's lawyer also told the court he did not want Ms Spears to be behind the wheel when their two sons are in her car, "to protect their safety".

In 2006, Ms Spears was photographed driving with son Sean Preston on her lap, and authorities visited her home to investigate.

Under current orders, Mr Federline has primary custody of their sons because Ms Spears had allegedly defied court orders - including an order to submit for drug-testing.

Ms Spears, 25, and Mr Federline, 29, were not present at the hearing.