Google, Facebook, Twitter and Microsoft have called on the US government to allow them to publish greater detail about requests they receive to hand over user data.
US government agencies can demand data from private companies under the Foreign Intelligence Surveillance Act (Fisa) with a national security letter (NSL), which prohibit public disclosure by the companies supplying the information.
The call comes after reports on the US Prism internet monitoring programme claimed US agencies had direct access to the servers of nine top technology companies, including Google, Facebook and Microsoft.
Documents leaked by former CIA technical assistant Edward Snowden have raised concerns in the US and Europe that the Prism surveillance programme infringes citizens’ privacy rights.
Although the US has confirmed the existence of Prism, most of the technology companies have denied giving direct access to servers, saying they complied only with specific, legally binding orders.
Google, Microsoft and Twitter publish transparency reports detailing how many government requests they receive for user data in various countries, but those for the US do not include Fisa requests or other NSL demands, according to the Guardian.
Microsoft said: "Our recent report went as far as we legally could and the government should take action to allow companies to provide additional transparency."
Read more about surveillance
- UK links to US internet surveillance remain unclear
- Incident reporting and employee surveillance laws in other countries
- Government tries again to control CCTV surveillance
- UK police forces form high-tech regional surveillance units
- Police use outdoor wireless mesh network for IP surveillance
- Lords' surveillance report vindicates ICO warning
The software maker said greater transparency on the requests would help the community understand and debate these important issues.
Google has blamed the non-disclosure requirements of the national security letters for fuelling speculation about what data is shared with government agencies, according to the BBC.
Google said publishing the number of NSL requests and Fisa disclosures will show compliance with these requests falls far short of the claims being made.
Facebook said it wants to provide a complete picture of the government requests it receives and how the social networking business responds.
Although Twitter was not named in reports about Prism, the microblogging firm said it would like greater transparency around national security letters and supported efforts to make that happen.
While US officials have called Edward Snowden a traitor, others have called him a hero for revealing the extent of US government internet surveillance.
WikiLeaks founder Julian Assange said Snowden had revealed one of the most serious events of the decade, which he described as “the creeping formulation of a mass surveillance state."