The Ministry of Defence (MOD) has admitted a third data breach involving the email addresses of vulnerable Afghans left behind after the British airlift from Kabul.
Defence Secretary Ben Wallace was told to "get his house in order" on Monday after the latest revelation suggested a total of 268 addresses have been exposed.
Mr Wallace said all three breaches were "mistakes" that took place in the Afghan Relocation and Assistance Policy (ARAP) casework team tasked with advising the vulnerable Afghan nationals.
He said they were the result of group emails being sent with addresses in the "carbon copy" field rather than the "blind carbon copy" field, which would have anonymised recipients.
The Defence Secretary said in a written statement to Parliament the actions were not "deliberate or negligent", but the "result of insufficient training and data-handling procedures".
Mr Wallace admitted the third, previously unknown data breach, occurred on 7 September and involved "an additional 13 email addresses not previously compromised".
Describing the breaches as "unacceptable", Mr Wallace added: "They were also a breach of the trust many former Afghan staff have placed in us to honour our commitment and do all that we can to keep them safe."
He said the errors arose from the "intense speed" and pressure under which the ARAP team was expanded.
"As a result, some members of the team were inexperienced and insufficiently trained for such casework management," Mr Wallace added.
Watch: In September, we spoke to Afghan interpreters desperate to escape Taliban rule in Afghanistan.
He added that two personnel have been assigned to other roles outside the ARAP team following the investigation.
Shadow Defence Secretary John Healey said: "These breaches pose a fundamental threat to our operational effectiveness and national security which must be addressed immediately and comprehensively.
"This is a basic issue of competence for this Government.
"Until the Defence Secretary stops these leaks our service personnel will rightly be wondering whether the MOD has their back."
More than 7,000 Afghan nationals, including former staff of the British mission and their families, have been relocated in the UK, according to Mr Wallace’s update.
He added that there are fewer than 200 remaining in Afghanistan as the UK continues "to work with urgency to relocate all those who remain via a range of routes".