LONDON - Britain's top transport official said Monday that a disk drive containing personal information on three million driving test candidates has been lost in the United States -- the latest in a series of government blunders over data.

Details on the candidates -- including names, addresses and email addresses -- held on a hard drive were lost at an Iowa storage facility, British Transport Secretary Ruth Kelly told lawmakers in the House of Commons.

Kelly's report follows the loss by tax officials of sensitive data -- including banking records -- on nearly half the population.

Two computer disks from a tax and welfare department containing names, addresses, national insurance numbers and, in some cases, banking details, for 25 million adults and children disappeared while being sent by internal mail, ministers said last month.

A series of reviews launched because of the errors has found that other government departments have concerns about data handling, but uncovered no new mishaps, Treasury chief Alistair Darling said in a statement to legislators.

The blunders have dented Prime Minister Gordon Brown's hopes of introducing a national identity card system, which the government says is vital to enhance security and control immigration.

"We've seen that trust in the government to handle data has been shattered," said Phil Booth, of the No2ID campaign group, which opposes identity cards. "People do not trust the government to look after their sensitive details."

Brown hopes the cards, which will hold biographical and biometric data, will be introduced in 2009. The estimated cost of the program is $11.3 billion.

Kelly said details on driving test candidates were stored on a hard disk drive and lost in May from a storage facility in Iowa City.

Britain's Driving Standards Agency had hired Pearson Driving Assessments Ltd. to process the results of written tests candidates take before a practical examination. The company is part of the London-based Pearson Group PLC, the international media and education company that also owns the Financial Times newspaper and Penguin Books.

Charles Goldsmith, a spokesman for Pearson Driving Assessments in London, said the information was sent electronically to a Pearson data center in Iowa City, then downloaded to a hard disk drive, which subsequently went missing. He said the company believes it was misplaced somewhere in the office.

"Pearson considers all data security very important and we deeply regret this incident," he said. "We don't believe it was stolen ... We have no evidence that the information has been accessed or misused in anyway."

He said the Iowa City police had been notified at the request of the British government.

"The hard disk drive contained the records of just over 3 million candidates for the driving theory test," Kelly said. "I apologize for any uncertainty or concern."

Kelly said her department had also lost details on 7,500 vehicles -- including the names and addresses of their owners -- which went missing in the mail as they were transferred from Northern Ireland to Wales.

An interim report on an inquiry by Gus O'Donnell, Britain's senior civil servant, said all government departments are reviewing data security.

Britain's Crown Prosecution service, which authorizes criminal prosecutions, is concerned about the use of portable media to access records and the encryption of backup files, the interim report said.