The Ministry of Defence (MOD) has apologised following a "data breach" that reportedly exposed the email addresses of around 250 interpreters who remain in Afghanistan.
Defence Secretary Ben Wallace has ordered an investigation into the apparent mistake involving the details of those who worked alongside British forces and who have applied to come to the UK.
The MOD says people affected have been contacted and are being offered advice on how to manage any potential risks they face.
An MOD spokesperson said: "An investigation has been launched into a data breach of information from the Afghan Relocations Assistance Policy team.
"We apologise to everyone impacted by this breach and are working hard to ensure it does not happen again.
"The Ministry of Defence takes its information and data handling responsibilities very seriously."
Responding to the Afghan interpreter data breach, Shadow Defence Decretary John Healey, said: "We told these Afghans interpreters we would keep them safe, instead this breach has needlessly put lives at risk.
"The priority now is to urgently step up efforts to get these Afghans safely to the UK.
"This is the second major data breach from the MOD this year, after sensitive documents were discovered at a bus stop in Kent in June.
"Clearly, the Defence Secretary needs to get his house in order."
The MOD has said it will take all necessary steps under UK GDPR (General Data Protection Regulation) rules.