The breach occurred at Inflite The Jet Centre Ltd, a sub-contractor providing ground handling services at London Stansted Airport, following a cybersecurity incident.
Affected individuals include Afghans resettled in the UK after assisting British troops, as well as those who travelled for routine military exercises.
Potentially leaked information includes passport details such as name, date of birth, passport number, and Afghan Relocations and Assistance Policy (ARAP) reference numbers.
This incident marks another data loss following a previous breach that exposed details of 18,700 Afghan applicants, raising concerns about the MoD's handling of sensitive data.