Firms call for 'substantial enhancements to privacy protections' and 'appropriate oversight' in letter to Senate committee

Tech giants including Apple, Facebook and Google called for substantial reforms to the US government's surveillance programmes Thursday in a letter to the Senate judiciary committee.

In the wake of more revelations about the lengths to which the National Security Agency has gone to intercept data, the companies have called for more transparency and "substantial enhancements to privacy protections and appropriate oversight and accountability mechanisms for those programs."

The letter, also signed by AOL, Microsoft and Yahoo, follows the release of more documents obtained by former NSA contractor Edward Snowden that reveal the US authorities were secretly tapping in to the tech firm's main communications links.

The letter "applauds" the USA Freedom Act, a bill sponsored by Democrat senator Patrick Leahy and Republican congressman James Sensenbrenner that would end the bulk collection of data from millions of Americans and set up a privacy advocate to monitor the Fisa court, which oversees the NSA's US activities.

"Recent disclosures regarding surveillance activity raise important concerns in the United States and abroad. The volume and complexity of the information that has been disclosed in recent months has created significant confusion here and around the world, making it more difficult to identify appropriate policy prescriptions," the letter states.

"Our companies have consistently made clear that we only respond to legal demands for customer and user information that are targeted and specific.

"Allowing companies to be transparent about the number and nature of requests will help the public better understand the facts about the government's authority to compel technology companies to disclose user data and how technology companies respond to the targeted legal demands we receive," they write.

In a recent report the Information Technology and Innovation Foundation (ITIF) said the US tech firms could end up losing out on tens of billions of dollars in the cloud-based computing space in the wake of Snowden's revelations. Cloud computing is a rapidly growing area and revelations that the US authorities have been scooping up the personal data of millions of users, particularly outside the US, could cost them business.

"On the low end, US cloud computing providers might lose $21.5bn over the next three years," ITIF concluded. On the high end the report put the figure at $35bn.

"We urge the administration to work with Congress in addressing these critical reforms that would provide much needed transparency and help rebuild the trust of Internet users around the world," the letter said.