Parents are to be given new powers to check with police whether people given regular unsupervised access to their children have convictions for paedophile offences, Home Secretary Jacqui Smith said yesterday.
The scheme will initially be trialled in four police areas - Warwickshire, Cambridgeshire, Hampshire and Cleveland - 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.
In an article in yesterday's 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."
Sara Payne, mother of eight-year-old Sarah Payne who was murdered in 2000 by Roy Whiting, said: "Almost eight years on and five Home Secretaries later, it seems we have finally reached at a stage where the Government is putting the safety of our children first.
"These new trials are a major step forward, helping us to protect our children and making it harder for those that prey on them to hide under the veil of state-assisted secrecy.
"For that we applaud the Home Secretary and her team, but there is still much work to be done."
Warwickshire Chief Constable Keith Bristow, who speaks for the Association of Chief Police Officers (Acpo) on violent crime, said: "Acpo have been working with the Home Office during the review period and are confident that the measures being taken will improve safety for our children.
"The police service is committed to protecting the most vulnerable groups in our communities and will implement the measures announced today by the Home Office.
"We look forward to evaluating the report back from the four sites involved in the dis-closure pilot in order to establish what additional protection this has provided to individuals and communities."
The plan, developed with police, will focus on the links between violent crime and alcohol.
A £1 million campaign will be launched this summer to warn youngsters that - far from making them safer, as many believe - carrying a knife heightens their chances of becoming a victim of violence.
And there will be new police resources for hundreds of metal-detecting knife arches and search wands in local communities.