The Serious Fraud Office says it has accidentally sent thousands of pages of evidence relating to an investigation into defence giant BAE Systems to the wrong person.
A statement from the office said it identified the data loss in May and that 98 percent of the material has already been recovered.
The office said that none of the material related to matters of national security.
More top news
A minute's silence will be held across the UK at midday to remember the victims killed in the Tunisia beach attack a week ago.
Jim Carrey apologises after using a photo of an autistic boy to promote his claims vaccines contain harmful neurotoxins
Newly released files show a proposal to move the population of Hong Kong to Northern Ireland