Gordon Brown has made a frank admission that government cannot promise the safety of personal data entrusted by the public.

The Prime Minister was speaking hours after it emerged that a memory stick containing the passwords to a government website used submit online tax returns had been lost.

Speaking on the second day of his trip to the Gulf, the Prime Minister said it was caused by "mistakes" which were “human”.

He also sought to clear government officials of blame, stressing that a private company – Atos Origin, a computer management firm – had accepted responsibility for the loss.

The Department for Work and Pensions was forced to shut down the Gateway service, which is used by consumers to pay parking tickets and fill in tax returns after the data, on a memory stick found outside a pub.

The loss by Atos Origin, which won a five-year £46.7million contract to manage the Government Gateway in 2006, was reported to the Government last week. The memory stick was found outside the Orbital Pub in Cannock and handed in to a Sunday newspaper.

Mr Brown said this was completely unacceptable, and warned that the company would be punished.

“I think that the company responsible has accepted responsibility and it is a private company. I think action will be taken by the Department of Work and Pensions. It’s not acceptable behaviour,” he told ITV News. He said that the company could expect “changes to the contract.”

The Government has faced repeated embarrassments over lost data, with 277 data breaches reported since 25 million child benefit records went missing nearly a year ago. Only last week James Purnell, the Secretary of State for Work and Pensions, was forced to apologise for leaving papers on a train. Mr Brown appeared to accept data loss in future was inevitable.

“It is important to recognise we cannot promise that every single item of information will always be safe because mistakes are made by human beings. Mistakes are made in the transportation, if you like in the communication, of information.”

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