The identities of more than 160 child sex offenders have been exposed during the first year of the "Sarah's Law" scheme, which allows worried parents to check on anyone who has regular access to their children.
The project is named after Sarah Payne, the eight-year-old murdered in 2000 by a convicted paedophile, Roy Whiting, and was rolled out across England and Wales exactly a year ago.
Theresa May, the Home Secretary, disclosed last night that police had received more than 1,600 enquiries and more than 900 formal applications under the scheme, which enables people to contact police to check whether those with access to a child pose a risk.
Ms May said more than 160 child sex offenders had been identified, while another 58 had committed other crimes. As a result of alerts being sounded, the Child Sex Offender Disclosure Scheme had saved more than 200 children from potential harm, she added.
Upon receiving an application to review an individual's background, police will reveal his or her details in confidence if they think it is in the child's interests. They can also warn parents if concerns are raised by grandparents or neighbours.
Ms May said: "We are doing everything we can to protect the public, and especially children, from predatory sex offenders by tightening the law and closing loopholes. But families themselves have a vital role to play. It is important that parents, guardians and carers are aware of the disclosure scheme and their right to request information if they have concerns."
Sarah's mother, Sara Payne, said: "If just one child had been kept safe as a result of Sarah's Law, then all the work to see it introduced would have been worth it."
The UK scheme is a diluted version of Megan's Law in the US, under which the names and addresses of convicted paedophiles are published.