The loss of thousands more people's personal records in the post undermines the government's case for ID cards, the Liberal Democrats said today.
Following the revelation that two computer discs containing the personal information of more than 6,000 motorists have been lost in the post, Alistair Carmichael, Lib Dem Northern Ireland spokesman, said the government was cavalier in the way it handles important information.
Today's admission by the Department of the Environment Northern Ireland, which oversees the Driving Vehicles Agency in the province, shows the loss of 25 million child benefit claimants' records by HM Revenue and Customs (HMRC) was not a one-off incident, Mr Carmichael claimed.
He predicted: "The political damage caused by yet another data breach will be significant.
"The proposed ID card scheme hinges on the government's ability to keep personal data safe."
It is now hard to imagine "even the most enthusiastic promoters of ID cards" still see their introduction as a good idea, Mr Carmichael concluded.
The Conservatives have also leapt on the latest security breach as prove of the government's "incompetence".
Shadow transport secretary Theresa Villiers said it "beggars belief" Labour could still be losing CDs with personal data in the post.
Ms Villiers said: "It looks like it has failed to learn anything from the HMRC catastrophe.
"Yet again we see Mr Brown's government failing its basic duty to run government competently."