Personal details of thousands of civil servants, including bank details of some, were on laptop computers stolen during a break-in at government offices in Northern Ireland, it was revealed today.

An urgent investigation was launched after computers were taken some time over the weekend from the Department of Finance and Personnel's Corporate Human Resources office in Upper Queen Street in Belfast city centre.

There are nearly 30,000 staff in the Northern Ireland civil service and it is now understood details including name, address, National Insurance number and date of birth, of possibly all of them, were on the laptops.

Bank account details of some were on one of the computers, and priority is being given to these cases, with banks already informed.

The Department said immediately after the robbery that in accordance with civil service data security procedures all of the laptops were password protected.

A spokesman added today: ‘The director of personnel for the Northern Ireland Civil Service has written to staff with more information on the recent break-in and will be issuing a statement in due course.’

An email circulated to staff said two laptops containing a wide range of personal data in a number of files had been taken.

It added: ‘This includes employee name, home address, payroll number, National Insurance number and birth date.

Separate details of some individuals' bank or building society accounts were contained on one of these laptops and these individuals are being contacted separately and immediately with more detailed information and advice.

Their banks have already been contacted.