Senior social workers have given warning of the dangers posed by a new government register that will store the details of every child in England from next year.

They fear that the database, containing the address, medical and school details of all under-18s, could be used to harm the children whom it is intended to protect.

The Association of Directors of Children’s Services (ACDS) has written to officials outlining its “significant” concerns about the new system, called ContactPoint, The Times has learnt. Confusion over who is responsible for vetting users and policing the system “may allow a situation where an abuser could be able to access ContactPoint for illegitimate purposes with limited fear of any repercussions”, Richard Stiff, the chairman of the ADCS Information Systems and Technology Policy Committee, said.

The security fears are fuelled further by the admission that information about the children of celebrities and politicians is likely to be excluded from the system.

The database, which goes live next year, is to contain details of every one of the 11 million children in the country, listing their name, address and gender, as well as contact details for their GP, school and parents and other carers. The record will also include contacts with hospital consultants and other professionals, and could show whether the child has been the subject of a formal assessment on whether he or she needs extra help.

It will be available to an estimated 330,000 vetted users. Some of those allowed to check records, such as head teachers, doctors, youth offender and social workers, are uncontroversial, but critics have questioned why other potential users, such as fire and rescue staff, will have access to the database.

ContactPoint was set up after the official report into the death of Victoria Climbié. Lord Laming concluded that the eight-year-old’s murder could have been prevented had there been better communication between professionals.

Regulations governing the system, which is costing £224 million to build and a further £41 million a year to run, were rushed through parliament without publicity last month, despite the warning of a House of Lords committee. “The enormous size of the database and the huge number of probable users inevitably increase the risks of accidental or inadvertent breaches of security, and of deliberate misuse of the data (eg, disclosure of an address with malign intent), which would be likely to bring the whole scheme into disrepute”, the Lords’ Select Committee on Merits of Statutory Instruments concluded.

Now local councils have given warning that changes made to the rules after consultation could leave the system open to abuse. The Association of Directors of Children’s Services has written to Christine Goodfellow, the official in charge of the new database, to register its fears over security.

In addition to its warning over vetting, the body says that ministers are placing “unreasonable and perhaps undeliverable expectations on local councils” by asking them to guarantee the accuracy of data over which they have little control.

Private schools and children’s rights campaigners have already given warning that the database is open to misuse. “Unless the system is secure, the result will be that sensitive information will fall into the hands of potential abusers of children and traders of information,” a letter signed by the Independent Schools Council, Privacy International and the Foundation on Information Policy Research said.

Concerns have been intensified by the admission that, while every child under 18 in England will have a record, ministers have allowed some children to be given extra protection. The “shielding” mechanism will mean that information on the offspring of some politicians and celebrities could be left off the main database.

A spokeswoman for the Department for Children, Schools and Families (DCSF) said that shielding would be available for “children whose circumstances may mean that they, or others, are at increased risk of harm”. She added: “These decisions will be taken on a case-by-case basis and will be based on the level of threat posed if their information becomes more widely available.”

Children’s rights campaigners and computer security experts say that this amounts to an acknowledgment that the database will not be secure. “The Government acknowledges the risks by instituting these protocols on celebrity and vulnerable children but all children are potentially vulnerable,” Terri Dowty, of Action on Rights for Children, said.

Ian Brown, a computer security research fellow at the Oxford Internet Institute, said that the scale of the database posed huge risks. “When you have got more than 300,000 people accessing this database, it’s just very difficult to stop the sale of information.”

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