Paul Gray, the chairman of HM Revenue & Customs, has resigned following the loss of two discs in transit carrying the details of 25 million child benefit recipients.
The loss of the discs is potentially the biggest identity theft scare to have taken place in the UK.
News of HMRC chairman Paul Gray's resignation broke earlier today.
Chancellor Alistair Darling is to make a statement to the Commons on the loss at 3.30pm today.
It is believed the loss was discovered over a week ago and the police are already investigating the case.
Names, addresses, dates of birth and bank account details are believed to be on the missing discs.
Some personal details of children are thought to have been included on the discs.
Opposition politicians have called for ministerial heads to roll over the affair, which comes hot on criticism over the way the government's Treasury has handled the Northern Rock situation.
It is not known whether the information being transported was encrypted for its protection, but it is being reported that their transportation breached rules governing data protection.
Last night, the BBC Watchdog programme had reported a wide range of incidents of personal data going astray at HMRC.