The lawyer representing Spears' ex-husband Kevin Federline in the extended legal wrangling told reporters the judge had extended her visitation rights, without providing details.

"We all see indicators of progress by Ms Spears," Federline's lawyer, Mark Vincent Kaplan, told reporters after the closed door hearing, which heard a report on Spears by a mental health expert.

"What was a seemingly daily state of extreme flux has been stabilized," Kaplan said.

Spears, 26, turned up at court on time, demurely dressed in a brown polka-dot dress and cream cardigan, and accompanied by her parents. It was a striking contrast to weekly court sessions of a few months ago when she failed to appear or left abruptly.

Spears was stripped last October of legal and physical custody of Sean Preston, 2-1/2, and Jayden James, 20 months. She lost the right to visit them in January but Federline agreed in February that Spears could occasionally see the boys under supervision. The singer has turned her life around in the past two months after a year of bizarre behaviour and two brief hospitalizations in Los Angeles for psychiatric evaluation.

Spears' father Jamie Spears was granted control over her personal and business affairs in February, and the singer's former self-styled manager and constant companion, Sam Lutfi, has agreed to a restraining order that keeps him away.

Spears won praise for a guest appearance on the TV sitcom How I Met Your Mother in March and is set to reprise her role as a office assistant on the show in May.

"We are so pleased at Britney's progress and we are very appreciative of the court's recognition of this progress," her parents said in a statement on Tuesday. Spears is due back in court in July for a further progress report.

The personal life of the former teen phenomenon, one of the most successful pop stars in the world in the early 2000s, spiraled out of control after her 2006 breakup with Federline.

She shaved her head, entered rehab, was ordered to take drug and alcohol tests and parenting classes, and was twice taken by ambulance to psychiatric units for treatment of what has been reported to be bipolar disorder.

Federline's spokesman, Elliott Mintz, told reporters that Federline was pleased by Tuesday's hearing. "At the end of this saga he is hoping and believing that there will be two children who are raised in the company of the two people who love them," Mintz said.