The decision was attacked by childcare experts who say the Government's alternative - a voluntary register of nanny agencies - will not ensure young children are protected.
Under the scheme, agencies that introduced extra checks on potential employees would be given a government "kite mark" of approval.
Margaret Hodge, the Education and Employment minister, said: "If you have a massive national register it becomes a bureaucratic nightmare. It's very difficult to keep accurate and up to date and police."
Announcing the plan, including new guidance for local authorities and parents, Mrs Hodge said the safety of children was "paramount". A call for new regulations follows cases where children have been harmed by professional carers. Other measures include the establishment of a Criminal Records Bureau to make police checks easier.
Louise Davis, principal of the Norland College in Berkshire, which trains nannies, dismissed arguments that a compulsory register would be cumbersome. She said: "It would be no bigger than the register of general nurses." There also needed to be nationally recognised training standards.
Cheryl Winton, founder of Playpen, a lobbying group on children's safety, said making the regulatory system voluntary would still leave less scrupulous agencies free to operate. Caroline Abrahams, head of public policy for the charity, NCH Action for Children, said childcare involved a constantly shifting population, often of young women, which would be difficult to monitor.
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