The White House and the National Security Agency (NSA) have dismissed reports that the spy agency had exploited the online security bug Heartbleed.
Their denial follows a Bloomsberg report which alleged that the NSA had willingly used the flaw to gather intelligence data.
The White House, the National Security Agency and the Office of the Director of National Intelligence issued statements on Friday.
The Heartbleed bug is understood to be one of the biggest internet security flaws to be discovered in many years.
It was uncovered by researchers with Google and security firm Codenomicon last Tuesday, which led to the US Homeland Security Department to advise businesses to review their servers to check if they were using vulnerable versions of the software called OpenSSL.
OpenSSL encrypts email and other forms of communication for the sake of consumer privacy, but the bug lets hackers steal data without leaving a trace.