WASHINGTON • Hackers who stole security clearance data on millions of Defence Department and other US government employees got away with about 5.6 million fingerprint records, some 4.5 million more than initially reported, the government said.

The additional stolen fingerprint records were identified as part of an ongoing analysis of the data breach by the Office of Personnel Management (OPM) and Department of Defence, OPM said in a statement on Wednesday.

The data breach was discovered in April and affected security clearance records dating back many years.

The news came just ahead of a state visit to Washington by Chinese President Xi Jinping. US officials have privately blamed the breach on Chinese government hackers, but they have avoided saying so publicly.

President Barack Obama has said cyber security will be a major focus of his talks with Mr Xi at the White House today. The United States has told China that industrial espionage in cyberspace by its government or proxies is "an act of aggression that has to stop", Mr Obama said recently.

The US said no evidence has surfaced yet suggesting the stolen data has been abused, though they fear the theft could present counter-intelligence problems. One of the biggest concerns has been that China, or other states given access to the data, could use it to identify intelligence agents, defence personnel or government contractors.

Other data on the forms that were obtained, about matters as varied as bankruptcies and personal and sexual relationships, could be used for blackmail.

White House spokesman Josh Earnest said on Wednesday that the OPM announcement was not related to Mr Xi's visit.

REUTERS, NEW YORK TIMES