"The FBI is working with our interagency partners to investigate the recently reported cyber intrusion at Sony Pictures Entertainment," a spokesman for the US federal law enforcement agency said in a statement.
"The targeting of public and private sector computer networks remains a significant threat, and the FBI will continue to identify, pursue, and defeat individuals and groups who pose a threat in cyberspace."
Various reports meanwhile said the hackers appeared to have posted online both confidential employee data and films not yet released in theaters.
The security blogger and researcher Brian Krebs said he discovered on websites devoted to illicit trading a "global Sony employee list," that included names, locations, salaries and dates of birth for more than 6,800 individuals.
"Another file being traded online appears to be a status report from April 2014 listing the names, dates of birth, SSNs (social security numbers) and health savings account data on more than 700 Sony employees," Krebs wrote.
The Washington Post reported meanwhile that the FBI was warning companies in a confidential memo about the malicious software used in the Sony hack.
An FBI spokesman said only that "we provided a routine notification to private industry," but declined to elaborate.
The spokesman added that the FBI "routinely advises private industry of various cyber threat indicators" to help protect computer networks.
Some reports in the past few days said Sony is looking into whether North Korea may have been behind the major cyberattack on the studio last week, possibly because of a upcoming comedy film about a CIA plot to assassinate its leader Kim Jong-Un.
"The Interview," which stars Seth Rogen and James Franco as two journalists recruited by the CIA to bump off Kim, has infuriated the North Koreans, with state media warning of "merciless retaliation."
The entertainment news site Variety has reported that unreleased Sony movies including the upcoming "Annie" have been made available on pirate file-sharing websites.
The war film "Fury" "Mr. Turner," "Still Alice" and "To Write Love on Her Arms" were also made available.
Sony did not respond to an AFP request for comment.
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