A blanket ban has been slapped on civil servants tempted to take laptops with unencrypted personal data out of their offices.

Reported by The Telegraph, the order was issued as it emerged that two more military computers, containing the sensitive details of thousands of people, had been missing for more than a year.

The command came from cabinet secretary, Sir Gus O’Donnell after Des Browne, the defence secretary, admitted a laptop stolen in Birmingham earlier this month was not encrypted and contained personal details on more than 150,000 people.

He revealed it was the third loss of a laptop with data since September 2005, the paper added. It also emerged that on two other occasions, Ministry of Defence laptops had been stolen with records that were not encrypted.

A further security breach occurred in October 2006, when a Navy laptop was stolen in Manchester, while an Army laptop with data on 500 people was also stolen from a recruiting office in Edinburgh in 2005.

According to the report, the security services were called in amid fears the information could contain the religious identities of applicants, putting Muslim recruits particularly at risk.