A recent hack attack on the U.S. government databases compromised the personal information of at least 21.5 million people, officials have said.
The Office of Personnel Management said that those affected included government job applicants, federal contractors, and over a million of their partners, reported the BBC.
The figure is at least five times higher than the number of people that were initially thought to have been affected.
The hack attack, which was uncovered in April, was blamed on China.
Meanwhile, Chinese authorities have denied any involvement.