The records of more than 3 million UK learner drivers have gone missing from a firm in the US, the government has admitted.

On the same day that the chancellor of the exchequer, Alistair Darling, updated the House of Commons about the investigation into HMRC's loss last month of 25 million child benefit records held on two CDs, transport secretary Ruth Kelly said that a data security audit in her department had revealed that a US contractor to the Driving Standards Agency had lost a disc containing the records of just over 3 million candidates for the country’s driving theory test.

The records contained on the hard disc included the names and addresses of the test applicants, their telephone numbers and in some cases an email address – but no financial data.

The driving test records cover the period from September 2004 to April 2007, and were actually found to have disappeared in May.

The government has sought to downplay the incident as minor in comparison with the HMRC breach.

Ms Kelly told the Commons that she had reported it to the information commissioner, Richard Thomas, and he had judged the risks presented by the loss were not "substantial" since bank account details and NI numbers were not included. He said that in the circumstances individual notifications did not need to be sent out.

But the minister apologised for any “uncertainty or concern” caused to affected individuals.

Shadow transport secretary Theresa Villiers said the breach was another blow to the government's plans "for an untested 'spy in the sky' national road-pricing scheme."

"How can the public possibly trust her department with information on every journey made by every one of the 33 million vehicles on Britain’s roads if it cannot be trusted with the data that it already has?" she asked.

Ms Kelly’s statement came after the Chancellor of the Exchequer told MPs that little progress had been made in the ongoing police inquiry into the loss of the 25 million child benefits held on two discs, despite the offer of a £20,000 reward for their return.

Mr Darling said that the police had no evidence of the data falling into the wrong hands and the banks had “no evidence of any activities suggesting evidence of fraud”.

Mr Darling said that Kieran Poynter, the PricewaterhouseCoopers chairman appointed to lead the investigation into the incident, still had much work to do in his investigation into data handling at HMRC.