Consultancy firm Deloitte has admitted that the loss of a laptop containing BSkyB staff pension details also included information about pension scheme members from Network Rail and British Transport Police.

The laptop theft – revealed exclusively by Computing yesterday – contained details of more than 100,000 people, including names, national insurance numbers and salaries.

BskyB told Computing that the laptop was protected by a number of security measures, including passwords, user IDs and encryption – a fact now confirmed in a statement from Deloitte.

"We believe that the likelihood of unauthorised access to the data held on this laptop is remote due to the opportunistic nature of the theft and the security controls," said the statement.

Both companies described the incident as being “opportunistic”.

“The thief could not have been aware that the bag – which was not a laptop bag – contained a laptop and therefore the theft was not targeted,” said BSkyB in a letter seen by Computing that was sent to all employees whose data may have been stored in the computer.

In a separate incident, the Ministry of Defence announced earlier today that it was investigating the loss of a computer hard drive that could contain the personal details of 100,000 members of the armed forces.