Google has sharply challenged the US government's gag order on its internet surveillance programme, citing what it described as a constitutional free speech right to divulge how many requests it receives from the government for data about its customers in the name of national security.
The move came in a legal motion filed in the secretive Foreign Intelligence Surveillance Court and is aimed at mending Google's reputation after it was identified this month as one of nine US internet companies that gave the National Security Agency access to data on its customers.
Revelations about the programme, known as PRISM, by former NSA contractor Edward Snowden has opened a debate about the privacy of American's communications.
The publication of such data requests by the government would answer questions about the number of Google users or accounts affected by US intelligence activities. But it would not answer more critical questions on how much data is being disclosed, including whether information belonging to Americans has been swept up into investigations on a foreign targets.
"Google's reputation and business has been harmed by the false or misleading reports in the media, and Google's users are concerned by the allegations," the company's motion says. "Google must respond to such claims with more than generalities."
Google has previously disclosed the number of data requests it receives from civilian law enforcement.
A company statement said that "lumping national security requests together with criminal requests - as some companies have been permitted to do - would be a backward step for our users".