Documents detailing Maxine Carr's new secret identity for her release from prison have been stolen from a car, it was revealed last night.

Sky News reported that the confidential details were taken in a raid on a Ford Fiesta near Hampstead, north London, shortly after 3.30pm on Tuesday.

It is understood the documents included Carr's new name, phone number and addresses of a safe house where she is expected to be held on her immediate release.

Police confirmed the articles belonged to two different women and said most of the items were recovered on Hampstead Heath at 7.15pm.

It is not thought thieves deliberately targeted the car, believed to belong to a female senior civil servant.

Police said the theft was opportunistic and confirmed that documents relating to Carr were later recovered.

Harry Fletcher, assistant general secretary of the National Association of Probation Officers, said he found news of the theft baffling.

He believed the issue of a new identity for Carr had not yet been fully discussed, and he understood that she was being relocated to a safe house, probably with her mother, who lives in Grimsby.

''The amount of surveillance was to be kept to a minimum and she would be supervised by a team of probation and police officers," he said.

However, Mr Fletcher accepted it was possible Carr had recently been persuaded to adopt a new identity.