A children's charity has called for an overhaul of the sex offender management system and the introduction of a contact point for worried parents to report their concerns.
The NSPCC wants the Government to ensure risk assessment of offenders is accurate, consistent and delivered on time.
It is urging swift action from police and other authorities when details of a suspected offender are reported and it wants to see the introduction of a service, such as a telephone helpline, where parents can get child protection advice.
The charity said its own investigations have revealed that children are being put at risk because of inconsistent policies from an under-resourced system.
Assessing risk is also hampered by the fact that many offenders do not come into contact with the criminal justice system and people do not know where to get help to enable them to spot abusers.
It believes more needs to be done to support child sex victims who can suffer lasting damage from their attacks.
It is currently estimated that nine out of 10 abused children do not receive substantial help.
Dame Mary Marsh, director and chief executive of the NSPCC, said: "Understandably the public have serious concerns about child sex offenders living amongst them.
"Parents want to be re-assured that their children are safe from attack and that sex offenders have been risk-assessed and are being properly supervised and appropriately housed. However it must be remembered that children are most at risk from people they know.
"The Government understands there are shortcomings in the existing system of managing offenders. We believe that an overhaul to give improved risk management, and better public education will help restore public confidence."
