Seven of the world's largest tech companies have signed an open letter calling for international governments to restore public trust in the Web.

The tech giants - also including LinkedIn, Twitter, AOL and Yahoo! - say they recognise the need for action to protect safety and security, but they believe the NSA's surveillance programme goes "too far".

Facebook CEO Mark Zuckerberg says, "Reports about government surveillance have shown there is a real need for greater disclosure and new limits on how governments collect information." 

Zuckerberg adds that the Obama administration should take the opportunity to lead reform and "make things right".

On a Reform Government Surveillance website, the companies state they "believe that it is time for the world’s governments to address the practices and laws regulating government surveillance of individuals and access to their information. While the undersigned companies understand that governments need to take action to protect their citizens’ safety and security, we strongly believe that current laws and practices need to be reformed."

They go on to list five 'guiding principles' they urge international governments to support, including 'limiting governments' authority to collect users' information' and 'respecting the flow of free information'.