BAE Systems has said that it is "concerned" to hear of the data loss, but that it is "a matter for the Serious Fraud Office".
The defence giant also confirmed in a statement that the material was not sent to a current or former employee of the company.
We were concerned to hear of this unfortunate incident but understand it has now been dealt with by the relevant authorities. Ultimately, this is a matter for the SFO and as far as BAE Systems is concernedit is now closed.
More top news
Fast-melting Arctic sea ice has forced some 35,000 Pacific walruses to retreat to the Alaska shoreline.
One of the most notorious Mexican drug lords still at large has been captured by soldiers at a seafood restaurant in a picturesque town.
A dossier of online abuse directed at the parents of Madeleine McCann is being examined by police.