Britain set up a secret scheme to relocate thousands of Afghans to the UK after a soldier accidentally disclosed the personal details of more than 33,000 people, putting them at risk of reprisals from the Taliban, court documents showed on Tuesday.

A judge at London’s High Court said in a May 2024 judgment first made public on Tuesday that about 20,000 people may have to be offered relocation to Britain, a move that would likely cost “several billion pounds.”

Britain’s current defense minister John Healey said that around 4,500 affected people “are in Britain or in transit … at a cost of around 400 million pounds.”

The government is also facing lawsuits from those affected by the breach, further adding to the ultimate cost of the incident.

A Ministry of Defence-commissioned review of the data breach, a summary of which was also published on Tuesday, said more than 16,000 people affected by it had been relocated to the UK as of May this year.