Mary Bell, who in 1968 at the age of 11 strangled two young boys, yesterday escaped from Moor Court open prison at Stoke-on-Trent, Staffordshire.

At her trial Mr Justice Cusack, in sentencing her to be detained at Her Majesty’s pleasure, said of Mary Bell: “This girl is dangerous and therefore steps must be taken to protect other people.”

But Inspector John Reynolds, of the Staffordshire police, said last night: “There is no organised search. The Home Office is quite happy that Mary Bell is not dangerous.”

“Bell killed some smaller children when she was 11 years old. Now she is 20 and prison authorities say she is not the slightest bit dangerous. She is just a missing 20-year-old from an open prison.”

During her nine-day trial the prosecution alleged that Mary Bell and a schoolgirl neighbour killed two boys, aged four and three, in Newcastle upon Tyne, “solely for the pleasure and excitement of murder.” But the jury acquitted the other girl and found Mary Bell guilty of manslaughter on the grounds of diminished responsibility.

Mr Justice Cusack said: “It is a most unhappy thing that in all the resources of this country it appears there is no hospital available which is suitable for the accommodation of this girl.”

Since then there has been periodic controversy over the conditions of Mary Bell’s detention. In 1972, when she was being held in the Red Bank approved school at Newton-le-Willows, Lancashire, the BBC programme Midweek claimed that as the only girl among 23 boys she was at the centre of a sex and pornography scandal.

In November, 1973, she was moved to the “secure” prison of Styal Cheshire, where subsequent appeals for parole were rejected.

Inspector Reynolds said that Mary Bell had disappeared from the prison at around tea-time with Annette Priest, a 21-year-old prostitute convicted of stealing from her clients. The two women had been seen by a warder, thumbing a lift in Cheshire.

There have been several sightings and police in the North have been alerted in case they attempt to reach Mary Bell’s home in Northumberland or Miss Priest’s home in Yorkshire.

Although the Home Office stresses that Mary Bell is no longer dangerous Mr John Stokes, the Conservative MP for Halesowen and Stourbridge, is to protest to the Home Secretary, Mr Merlyn Rees, that Mary Bell was in an open prison “and not behind bars.”

Mary Bell was returned to prison not long after her escape. She was released in 1980 and granted lifelong anonymity in 2003.