The Conservatives have warned that taxpayers may have to foot a huge compensation bill after the personal details of thousands of criminals were lost in the latest government data blunder.
The names, addresses and expected release dates of all 84,000 prisoners in England and Wales were among the information on a computer memory stick lost by Home Office contractor PA Consulting.
It also contains the names, addresses and dates of birth of 30,000 people with six or more convictions in the last year, as well as the names and dates of birth of 10,000 offenders regarded as prolific and the initials of people on drug treatment programmes.
The Tories said the British public would be "absolutely outraged" if it had pay compensation following the loss of the memory stick, while the Information Commissioner's Office warned that "serious questions" would need to be answered.
The Home Office was informed on Monday that the stick might be missing and on Tuesday PA Consulting finally confirmed to home secretary Jacqui Smith that it had vanished.
An internal investigation was launched but it took until Thursday before police were called in to help.
A Home Office spokesman said: "We have been made aware of a security breach at the offices of an external contractor involving the loss of personal information about offenders in England and Wales.
"A full investigation is being conducted. Police and the information commissioner have been informed."
Shadow home secretary Dominic Grieve described the loss as a "massive failure of duty".
"The British taxpayer will be absolutely outraged if they are made to pick up the bill for compensation to serious criminals," he added.
And Liberal Democrat leader Nick Clegg said it raised questions about whether the government could be trusted to keep any information safe.
"Charlie Chaplin could do a better job running the Home Office than this Labour government," he said.
"The government will no doubt seek to blame private contractors, but the rash of data losses over the last two years confirm that there is something much more worrying at stake: this government cannot keep any information safe."
It is the latest in a line of data loss incidents over the past year.
