IT glitches are threatening the security of the Contactpoint child database.
The internet database will hold the personal details of every child in the UK, and will be accessed by hundreds of thousands of workers involved in child protection.
It is supposed to have a shielding system preventing users from seeing details on victims of domestic violence, children in witness protection programmes and those involved in difficult adoptions.
Most children will have their names, addresses, dates of birth, and school, GP and social services details. Users should only be able to see the name, sex and age of a shielded child.
But local authority staff have found that the system does not always work while they were uploading information onto the database, the Times reported.
The Department for Children, Schools and Families (DCSF) has ordered a pause in the data upload while engineers investigate the problems.
In some cases, adopted children who should be shielded are listed on the database under their former surname and their adoption surnames. The two are then linked. It means abusive parents who had their children removed from them could track them down to their new adoptive families.
There are also problems with other major databases that Contactpoint links to. Every time the Department of Work and Pensions, for example, updates its central information on child benefits, the shielding on vulnerable children disappears. All their information becomes available on a duplicate record that somehow gets created.
Contactpoint was one of the projects singled out for criticism in a recent report looking at the legality of the UK's major databases. It has suffered a series of setbacks with launch dates being postponed due to technical problems.