Britney SpearsBritney Spears has been hospitalised and possibly arrested after a “family custody dispute” at her Beverly Hills home last night.

Police were called to the property around 8pm local time (4am GMT) after Britney reportedly refused to hand back son Jayden to ex-husband Kevin Federline followed a visitation session (older son Sean had been allowed to leave earlier in the evening).

When the officers arrived at the home, they found the court-appointed visit monitor had been locked out of the house and was not in possession of the paperwork required to allow them to enter Britney’s house and retrieve the remaining little boy.

By 10.30pm, Kevin’s lawyer Mark Vincent Kaplan had supplied the police with the required documents and he and five police cars entered the estate and drove up to the house. Shortly afterwards, Britney’s assistant Carla and her cousin Alli Sims left the house, leaving Britney alone inside with her 15 month old son. Additional police cars, a fire engine and a police helicopter were said to be on hand amidst reports claiming that Britney had threatened to hurt either herself or Jayden and onlookers described the event as looking like a “hostage situation”.

Around 11.30pm, the group finally entered the building and around 11.45pm, Britney was taken out of the house strapped to a stretcher and was placed in an ambulance. She was then taken to Cedars-Sinai Medical Center accompanied by a police officer and led by a police escort of 13 squad cars. Jayden was also taken to the hospital in a separate vehicle and was spotted quietly sucking a dummy as he was carried into the emergency room.

A police spokesperson has said Britney was taken to hospital because there was concern for “her mental state and [we] believe she may be under the influence” of an “unknown substance”. She is said to have undergone a mental evaluation when she was admitted to the medical centre and hospital sources say she will be kept on a “mental lockdown” for a minimum of 72 hours.

Sources differ as to whether the singer was placed under formal arrest but the presence of a police officer in the ambulance may have been a sign that she was in police custody from that point. Another source told OK magazine that she will remain under guarded observation at Cedars-Sinai for 24 hours then if she is deemed fit, she will be arrested.

LAPD spokesperson Jason Lee confirmed the evening’s events and added: “At this stage we do not know what she may or may not have taken - that’s why she needs to be evaluated.”

“But obviously if the [drink and drug] test does prove positive, then we would be looking to move her to a police station and charge her.”

Earlier in the day, Britney had attended a scheduled deposition hearing with Kevin’s legal team. The meeting was scheduled to take place between 9.45-11.45am but Britney only arrived at around 11.30, allowing just 14 minutes of questioning before leaving at the scheduled finishing time.

Kaplan has described her as “cooperative” during her brief appearance but added: “You can imagine in 14 minutes there’s not a lot of time to develop questions.”

“I would’ve preferred it had gone on longer. There has been no change in anything. It will be continued to another date, which I will not say at this time.”

Britney had missed earlier scheduled deposition hearings - one on Wednesday and one last month - and her unwillingness to attend the sessions is said to be part of her lawyer Sorrell Trope’s decision to ask to withdraw from her case.