Photo: AP

(Bloomberg) — Hackers in China breached U.S. Office of Personnel Management computers and stole personal records of as many as 4 million current and former federal employees, a U.S. official said.

The hackers, believed to have links to the Chinese government, got into the government computer system last September, according to the official, who asked for anonymity to discuss the investigation.

A U.S. intelligence official said, also speaking on condition of anonymity, Chinese hackers appear to have mounted an effort to get personnel files, health-care records and other personal information on millions of government employees and contractors.

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The data could be used to target individuals with access to sensitive information who have financial, marital or other problems and might be subject to bribery, blackmail, entrapment and other traditional espionage tools, the official said.

The Federal Bureau of Investigation and the Department of Homeland Security are investigating the hack, which was detected in April, according to a statement from OPM.

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The federal government plans to notify those who were potentially affected by the breach, and is offering free credit report access, credit monitoring and identity-theft insurance and recovery services to those whose personal information was compromised.

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