Sony Pictures is looking into whether North Korea may have been behind a major cyber attack on the studio last week.
It was reported that the attack came as the studio prepares to release a comedy about a CIA plot to assassinate North Korean leader Kim Jong-Un.
"The Interview," which stars Seth Rogan and James Franco as two journalists recruited by the CIA to kill Mr Kim, has infuriated the North Koreans, with state media warning of "merciless retaliation".
The re/code website reported that Sony and outside consultants were exploring the theory that hackers operating in China carried out the attack last Monday on behalf of North Korea.
A North Korean link has not been confirmed by Sony Pictures.
Meanwhile, the US Federal Bureau of Investigation has warned American businesses that hackers have used malicious software to launch destructive attacks in the United States.
The five-page confidential "flash" warning was issued to businesses late last night.
It provided some technical details about the malicious software that was used in the attack, but it did not name the victim.
Two cyber security experts who reviewed the document and were familiar with the Sony attack said that they were sure the agency was referring to the breach at the California-based unit of Sony.
"This correlates with information about that many of us in the security industry have been tracking," said one of the people who reviewed the document.
"It looks exactly like information from the Sony attack."
FBI spokesman Joshua Campbell declined to comment when asked if the software had been used against the California-based unit of Sony.
However, he confirmed that the FBI had issued the confidential "flash" warning.
"The FBI routinely advises private industry of various cyber threat indicators observed during the course of our investigations," he said.
"This data is provided in order to help systems administrators guard against the actions of persistent cyber criminals."
It does not name victims of attacks in those reports.
The report said the software overrides data on hard drives of computers and can make them inoperable and shut down networks.
