During an ongoing analysis of the data breach, the estimated number of people who had fingerprint records stolen rose from 1.1 million to about 5.6 million, the OPM said in a statement obtained by Reuters.
According to the OPM, an estimated 21.5 million people had their Social Security numbers and other personal information stolen in the hack earlier this spring.
Some US officials have publicly blamed the Chinese for the attack, but have failed to produce any evidence for the accusation.
Officials also have said no evidence has surfaced yet suggesting the stolen data has been abused, though they fear the theft could present counterintelligence problems, Reuters reported.
The OPM said it learned of the additional stolen fingerprints as the agency and the Defense Department were analyzing data affected by the breach.
The stolen fingerprints currently pose only a limited threat, the agency said, but also acknowledging that the threat could increase over time as technology evolves.
Therefore, a working group – comprised of experts from the intelligence community, the FBI, Department of Homeland Security and the Pentagon – will review the potential ways enemies could misuse fingerprint data now and in the future.
"If, in the future, new means are developed to misuse the fingerprint data, the government will provide additional information to individuals whose fingerprints may have been stolen in this breach," OPM said.
