ContactPoint, a database of all the children in the UK, has been "paused" after security flaws were found.
Development work on the controversial 224 million database was temporarily halted after problems were discovered in the system shielding details of vulnerable children, the Department for Children, Schools and Families (DCSF) said.
The problem comes just days after a report said the ContactPoint database could be illegal.
A department spokeswoman said in a statement: "We have paused the ongoing data update while we investigate. We will not restart it if there is risk of introducing unmatched records for children whose existing ContactPoint records have been shielded."
The statement added: "Local authorities are already shielding records where they judge that there is a risk to a child or family or the adoption placement. We have been made aware that in some instances identities might be linked. We are working with national data sources to resolve this issue."
Shadow Children's Minister Tim Loughton said: "The Government has proved that it cannot be trusted to set up large databases or to keep our data secure. Despite serious and widespread concerns about the security, integrity and necessity of this database, ministers seem determined to bulldoze it through."
ContactPoint faced delays after the HMRC breach in 2007, so ministers could audit security measures, while a report since then has said that the database can never be considered fully secure.
