'Sarah's Law' scheme to be piloted

The scheme will initially be trialled in four police areas - Cambridgeshire, Hampshire, Cleveland and Warwickshire - and if successful could be rolled out across England and Wales.

It will allow single mothers to ask police whether potential boyfriends have child sex convictions before they start a relationship. And family members or neighbours who regularly look after children could also be checked.

Police and probation services will have discretion on what information is revealed in each case and disclosure will be carefully controlled. But it is understood that if children are thought to be at risk, parents and carers will be told.

Announcing the scheme in an article for the News of the World, Ms Smith said: "I am announcing that this summer, four police forces will start schemes that allow a child's parents or guardians to be informed if someone they are having a personal relationship with has previous convictions for child sex offences.

"We are working with the four selected forces across the country - in Cambridgeshire, Hampshire, Cleveland and Warwickshire - as well as with leading children's charities to develop these pilot schemes."

The News of the World hailed the announcement as a victory in its long-running campaign for a "Sarah's Law" allowing parents to obtain details of convicted paedophiles living in their neighbourhoods.

The campaign was named after eight-year-old Sarah Payne, murdered in 2000 by Roy Whiting, who had previously spent time in prison for the indecent assault of a girl.

Paul Cavadino, chief executive of crime reduction charity Nacro said: "We support a controlled experiment providing information to parents whose children are being targeted by paedophiles. However, there will need to be stringent safeguards to prevent abuse of the system by people wanting information in order to carry out vigilante attacks.

"The Government was right to resist pressure for a full system of public disclosure. General public disclosure would have caused offenders to go to ground, making it difficult or impossible for the police and probation service to keep track of them. This would have increased rather than reduced risk to children."