Ed Balls: ''This is a system which will make our children safe''
Concerns over the way a new vetting system for people working with children operates are "legitimate", the man tasked with reviewing it has said.
Head of the Independent Safeguarding Authority, Sir Roger Singleton, said he hoped to make the scheme clearer but insisted it was necessary.
The Conservatives said it could affect the running of sport and other clubs.
The system requires those working with children to be on a suitability register which employers can check.
It applies to England, Wales and Northern Ireland.
Sir Roger told the BBC's Today programme: "This opportunity to take a fresh look does provide us with the chance to listen carefully to those people who have expressed concern and to see whether we can get something that is more acceptable and something that is more straightforward."
He added he was surprised some of the "legitimate" concerns now expressed were not raised when the scheme was first set out in legislation three years ago.
England's Children's Secretary Ed Balls stressed the rules would not apply where, for example, parents agreed to give friends' children "a lift to school or to Cubs".
"Nor will it cover instances where parents work with children at school or a youth club on 'an occasional or one-off basis'," he said.
Defending the scheme and the review, Sir Roger said: "It's quite reasonable for any parent to expect that if their school offers to provide transport... those people have been vetted to the point where there is no known reason why they should not work with children".
Shadow Home Secretary Chris Grayling said: "All of this is so vague that in reality clubs and other organisations up and down the country will act to be on the safe side.
"So they'll register all of the parents who are involved even loosely. So the result is we'll get this huge expensive and cumbersome bureaucracy as well as volunteers giving up."
Lib Dem home affairs spokesman Chris Huhne welcomed the review as the plans "were so disproportionate that they were going to put off masses of people from volunteering".
Children's charity the NSPCC said new procedures were needed but called on the government to provide more detailed information about how the scheme would work.
Parents taking children to sports clubs regularly may be affected
Mr Balls said the scheme had been introduced via legislation in parliament, following the Bichard inquiry into the murders of two schoolgirls in Soham in 2002.
It requires those working with children or with vulnerable adults, either on a paid or voluntary basis, to be on a register of suitability which employers can check.
The police officer who led the Soham investigation criticised the system for going too far and said it needed to "get back on an even keel".
Retired Det Ch Supt Chris Stevenson said no amount of legislation or checking could stop all child murders by paedophiles.
The system will be phased in from next month and will operate in England, Wales and Northern Ireland from next year. A different scheme is being introduced in Scotland.
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