Google, Facebook and Microsoft have asked the US government to allow them to disclose the security requests they receive for handing over user data.
The move comes after recent reports claimed that US authorities had direct access to the servers of nine major US tech firms, including Google and Apple.
Google said the claims were "untrue" but added that nondisclosure rules of such requests "fuel that speculation".
The US has confirmed that the surveillance programme exists.
But it is coming under increasing pressure from many different quarters to end the practice.