They were copied into an email asking for more details about their situations, with every address visible to others it was sent when they should have been kept private.
Some of the email addresses had photographs attached to them, the BBC reported.
They said that those affected were seeking relocation to the UK, and many of them were in hiding.
Some had managed to get to a different country but sought to settle here, while others remained in Afghanistan.
Those affected have been notified of what happened.
Defence Secretary Ben Wallace has ordered an investigation into how this happened, calling it an ‘unacceptable breach’.
The email as sent as part of the UK’s Afghan Relocations and Assistance Policy (ARAP), which is aimed at helping those who helped British forces escape the country.
It told interpreters that Britain was working to help relocate them, and that they should not put themselves at risk if it wasn’t safe to leave where they were currently.
One of those who received the message told the BBC: ‘Some of the interpreters didn’t notice the mistake and they replied to all the emails already and they explained their situation which is very dangerous.’
Half an hour after sending the email the MoD emailed again asking people to delete the previous email and advising them to change their email address.
Afghans who worked with American and British forces are at risk of reprisals from the Taliban, who took over the country last month.
Shadow defence secretary 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.’
A spokesperson for the MoD 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.’
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