The Ministry of Defence has apologised and launched an investigation into a data breach that has “needlessly put lives at risk” by revealing the email addresses of more than 250 Afghan interpreters who worked for British forces.

An email sent by the MoD to interpreters who are seeking relocation to the UK asking for an update on their situation mistakenly copied in their email addresses, so they were visible to all other recipients.

The ministry says it has contacted the individuals affected by the data breach and is offering advice on how to manage the potential risks.

Many of the people who worked with western forces are in hiding from the Taliban, which seized power in August with surprising speed as the West withdrew in the run up to the 31 August deadline set by the US president, Joe Biden.

While more than 17,000 people were rescued by the UK – the largest refugee evacuation since the second world war – chaotic scenes at Kabul airport meant many of those who had assisted British troops were left behind.

The email came from the Afghan Relocations and Assistance Policy (Arap), which has been helping those still stuck in the country – as well as people who fled to neighbouring countries – after UK troops pulled out.

It advised those still stranded that Arap was doing everything possible to get them to safety and not to risk leaving their current location if it was not safe.

But one interpreter who received the email told the BBC: “This mistake could cost the life of interpreters, especially for those who are still in Afghanistan.

“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. The email contains their profile pictures and contact details.”

Ben Wallace, the defence secretary, told the BBC that the error was an “unacceptable breach”. The former defence minister Johnny Mercer said the error was likely to mean Afghan translators would be “moving house again tonight”.

He tweeted: “The truth on how we have treated our Afghan interpreters will come out.

“All the back slapping over [Operation] Pitting masks a criminally negligent performance by the Ministry of Defence and the Home Office on doing our duty to these people.”

John Healey, the shadow defence secretary, 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.”

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.”

The spokesperson added that it would be inappropriate comment on the specifics of the case at this time but that the department is taking all necessary steps under UK GDPR.