The temporary halt to work on the £224 million database comes only a day after a major review said work should be stopped on the database – and a number of other large databases – over privacy grounds.

That review branded ContactPoint and other databases “almost certainly illegal” on privacy and human rights grounds. There were also no decent options to opt-out and “inadequate” security, it said.

In a new security worry today, local authority staff uploading information to the database have found that shield systems for vulnerable children are not always working.

The systems are supposed to remove all details of vulnerable children – including victims of domestic violence and those in witness protection schemes – from the record, except their name, sex and age.

For some adopted children, their original and adopted names are being linked on the database, potentially allowing adopted children to be tracked down at school by their birth parents, observers noted. On other occasions, duplicate records revealing all the details of individual vulnerable children are appearing unexpectedly on the database.

A spokesperson at the Department for Children, Schools and Families, which runs the database, said it has “paused the ongoing data update” while it investigated the problems and until local authorities were “satisfied that these issues have been addressed”.

But Annette Brooke, Liberal Democrat spokesperson for children, said: “We cannot have some of our most vulnerable children being put at risk.” Conservative shadow children's minister Tim Loughton added: "The government has proved that it cannot be trusted to set up large databases or to keep our data secure."

The ContactPoint system, built by Capgemini, will see the names, addresses, schools and GPs of all 11 million under 18's listed in a database which is only intended to be accessed by professionals working with children, such as social workers, doctors and the police.

The project has been hit by a string of delays amid concerns over security, and finally launched in January, even though security concerns remained.

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