Thousands of Afghans have been offered asylum in the United Kingdom through a secret £850m relocation scheme intended to protect individuals whose personal information was included in a data breach.

So far, 4,500 Afghans have come to the U.K. as part of the program. An additional 600, along with their immediate families, are set to arrive soon. The secret plan has cost £400m so far, and the Ministry of Defense is projecting a further cost of £400m to £450m. In U.S. dollars, this program will cost more than $1 billion.

Furthermore, 17,000 Afghans set to come to the U.K. under a separate relocation scheme were also affected by the breach, officials said. Out of this group, 14,000 are in Britain or are in transit, and 3,000 more are set to come.

A spreadsheet containing information for 19,000 people who applied to move to the U.K. through the Afghan relocations and assistance policy (Arap) following the Taliban’s takeover was mistakenly shared by a Royal Marine in February 2022. The Ministry of Defense became aware of the data breach in August 2023 after some of the information was posted on Facebook. As many as 100,000 people were affected by the leak.

The government fought a lengthy legal battle to keep the information a secret and secured a superinjunction that prevented media organizations from reporting on the breach. The superinjunction was lifted on Tuesday.

Defense Secretary John Healey said the government was ending the program, but would not rescind offers already made to people in Afghanistan. He apologized to those whose information was included in the leak while speaking in the House of Commons.

He called the leak a “serious departmental error” that occurred “outside of authorized government systems.” He said an independent review found it was unlikely that those whose information was included would be targeted by the Taliban.

Healey did not say how many people had been killed or detained as a result of the leak. Those relocated to the U.K. have already been counted in immigration numbers, he said.

The program started under the previous government, and Healey said he was informed of it while serving as shadow defense minister. However, he could not speak publicly about it because of the superinjunction, which he called “unprecedented.”

“I have felt deeply concerned about the lack of transparency to Parliament and the public,” Healey told members of Parliament.