Alistair Darling speaks at the House of Commons.[Agencies]
Britain's Treasury chief tried to reassure Britons their personal details were safe after the one of the biggest security breaches in the country's history - the loss of two computer disks containing details about almost half the population.
Experts said the loss left millions of people exposed to identity theft and bank fraud.
"I can well understand people's anxiety and anger that this has happened. It should never have happened, and I apologize unreservedly for that," Chancellor of the Exchequer Alistair Darling told GMTV television.
There were gasps from lawmakers in the House of Commons on Tuesday when Darling described the scale of the loss by the country's tax and customs service.
Two computer disks that went missing in the post while being sent from one government department to another contained names, addresses, dates of birth, national insurance numbers and in some cases banking details for 25 million adults and children, almost half the country's population of 60 million.
"I regard this as an extremely serious failure," Darling told lawmakers in the House of Commons.
Paul Gray, chairman of HM Revenue & Customs, has resigned over the error.
HM Revenue & Customs is responsible for collecting taxes, distributing some welfare payments and carrying out border checks.
Darling said the disks contained details of the 7.25 million families in Britain claiming child benefit - a tax-free monthly payment available to everyone with children.
He said the delivery was not being tracked and was missing for three weeks before any alarm was raised.
He insisted there was no evidence the data had fallen into the hand of criminals, and said police were involved in a hunt for the missing disks. He said banks had been told to look for signs of suspicious activity, he said.
The disks were password protected, but the information on them was not encrypted, officials said.
"The police told me there is no evidence there has been any criminal or unusual activity," Darling said.
Information Commissioner Richard Thomas, the official charged with overseeing data protection, said the lapse was "a shocking case".
"I am at a loss to find out what happened in this situation. It is not just about the law. It is about retaining the trust and confidence of the population where so much information is entrusted to government," he told the BBC.
Conservative Party home affairs spokesman George Osborne said the government needed to "get a grip and deliver a basic level of competence".
（英语点津 Celene 编辑）