Britney Spears' effort to regain access to her two small children will go back to court on Monday for what a lawyer described as "the most significant hearing in the case so far".

Police and emergency medical technicians who were summoned to the singer's Los Angeles home on January 3 in a stand-off involving her refusal to return the boys to ex-husband, Kevin Federline, will testify, probably behind closed doors, Mr Federline's lawyer said.

"I don't know if she will be there," Mark Kaplan said, but he suggested she would have to appear in person if she wanted to press her request to see her children.

"You can't phone this one in," he added.

If Spears comes to court, Mr Kaplan said she would be expected to testify. "She will have the opportunity to persuade the court that she can have some visitation under monitored conditions," he said.

Phone and email messages requesting comment from Spears' lawyers were not immediately returned.

Mr Kaplan said he knew it was only a temporary measure when he obtained emergency court orders two weeks ago granting sole physical and legal custody to Mr Federline.

"These are very, very draconian orders," he said. "Because of that the court wanted to have a hearing to give her and her attorneys the opportunity to refute some of the declarations.

"No judge likes making orders terminating a person's involvement with their kids."

Meanwhile, police were preparing for a media frenzy in the downtown Los Angeles civic centre if Spears appeared, issuing warnings that vehicle and pedestrian offences would lead to prosecution.