A leading children's charity has said that government moves allowing parents the right to information about people in contact with their child could hinder work to manage sex offenders.
The NSPCC said it was concerned that inappropriate information could be given out to parents, unless clear guidelines were established and sufficient resources put in to implement them.
The plan to allow parents or guardians to ask for information about possible child sex abusers is one of a series of new measures due to be announced by the Home Office.
These will also include offering more "chemical castrations" to serious offenders, although these would remain a "treatment" and would not be required.
The NSPCC Director Mary Marsh said the plans could affect the care of around 30,000 known offenders living outside of prison.
The government should introduce a "fail-safe" system that will ensure all children are fully protected, she said.
"We always urge members of the public to report their concerns, but agencies are already struggling to keep track of known offenders in the community," said Marsh.
She said the police dealt with around 5,000 reports of children who have been raped every year.
"Investigating reports of sexual offences against children, bringing offenders to justice and managing them when released into the community is placing severe strain on agencies," Marsh said.
For the first time, proposals for England and Wales could give parents, guardians and carers some access to details about convicted paedophiles.
A review into how information about child sex offenders should be handled has been completed by the Home Office. For example, mothers could request a police check if they have concerns about a new partner, for example.
However, ministers are expected to rule out adopting a version of the " adopted in the United States, which allows widespread access to details about sex offenders.
Castration should be compulsory for sex offenders, says Sara Payne, who has been fronting a campaign for a British version of the U.S. "Megan's Law". The law allows widespread access to details about sex offenders.
Payne, whose daughter Sarah was murdered by a convicted paedophile in 2000, told the BBC: "You are placing an honour-based system on people who have already shown they have absolutely no honour."
"These are people that rape, molest our children, take photographs of what they are doing, they have already shown that they are of the nastiest people in the world because of what they do to children."
