The consulting firm responsible for the loss of personal details on 84,000 prisoners will continue to work on the children's database, sparking fresh concerns about the controversial project.

PA Consulting was recently dismissed by the Home Office after losing a memory stick containing information on all prisoners in the UK.

The ContactPoint children's database was delayed last year following a separate incident, in which discs containing information on 25 million families were lost.

Two weeks ago it was announced that the database, due to go live in October, would be delayed until January.

The announcement came only days after MPs and children's rights groups reacted furiously to the news that police would be able to apply to access the information for crime prevention and prosecution purposes.

PA Consulting's involvement with the project has renewed these concerns.

"Serious concerns have already been raised about the security of the database," David Laws, Liberal Democrat Shadow Children, Schools and Families Secretary, told Telegraph.co.uk.

"The revelation that PA Consulting Group is also involved will do nothing to reassure parents that their children's personal details will be secure. This intrusive and costly project must now be scrapped altogether."

PA Consulting was appointed in 2004 to work on the UK's National Identity Cards scheme.

When approached by Computing, a spokesman for the Identity and Passports Service said: "PA Consulting have six contracts with us, but we are not going into detail about the nature of those contracts."