Work has been halted on ContactPoint, the £224m database designed to hold the details of 11 million children under 18, while problems in the system are ironed out.

The problems centre on the so-called "shielding" part of the system, which protects certain elements of the details of 55,000 vulnerable children.

Most children's records contain their name, address, date of birth and details of schools, GPs, social workers and support services. But some vulnerable children are shielded to provide only their name, sex and age to the 400,000 children’s services workers with access to the database.

But this shielding has disappeared from the records of some children when information is uploaded to the database.

A third of England's 150 local authorities have not yet signed off the first phase of ContactPoint and many refuse to do so until the problems are sorted out.

A spokeswoman for the Department of Children, Schools and Families insisted the problem will not delay plans for the system to go live this year.

"Our colleagues have been working very quickly with local authority representatives to put the problems right. Fifty per cent of problems flagged up have already been identified as human error," she said.

She added that the unshielded details had only been exposed to the 300 local authority workers who were updating the system, all of whom had been vetted and cleared to access the children's information.

Tim Loughton, shadow children's minister, said the government could not be trusted to set up large databases.

"ContactPoint is not even live and it is coming apart at the seams. The government should have foreseen these issues five years ago when they first drew up plans for this expensive and unnecessary database," he said.