Eight of the world's largest technology companies have united to express their concern over government spying of civilians in an open letter to US president Barack Obama.

US technology companies speak out against NSA collection of their users' data. (Reuters)

Formed by AOL, Apple, Facebook, Google, LinkedIn, Microsoft, Twitter and Yahoo, the group is pushing for governments to address the practices and laws regulating the mass surveillance of citizens, as exposed by documents leaked by NSA whistleblower Edward Snowden.

Writing in an open letter to President Obama, the group says spying by governments "undermines the freedoms we all cherish."

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It added: "We understand that governments have a duty to protect their citizens. But this summer's revelations highlighted the urgent need to reform government surveillance practices worldwide. The balance in many countries has tipped too far in favour of the state and away from the rights of the individual - rights that are enshrined in our Constitution...It's time for a change."

The formation of the group comes after the companies were implicated in stories of widespread monitoring and the collection of personal communications data by the US National Security Agency and its UK counterpart GCHQ.

It is claimed in documents leaked by Snowden that governments have the ability to tap into the servers of companies like Facebook and Microsoft, where they can spy on civilians, collecting emails, phone records and more.

A call for change

The group calls on governments to put five new principles into action. To limit governments' authority to collect users' information; to implement a clear legal framework under which government surveillance agencies must operate, including independent courts who make rulings public in a timely manner; to allow companies to publish the number and nature of government demands for user information, and for governments to also publish a record of their requests.

The technology companies also want to see governments respect a free flow of information - meaning governments should not inhibit access by companies or individuals to lawfully available information that is stored outside of their country; governments should also not require service providers to locate infrastructure within their native country's borders.

Finally, the group wants a legal framework which applies equally across jurisdictions in order to prevent surveillance laws of one country conflicting with those of another.

A need for greater disclosure

Facebook CEO Mark Zuckerberg said: "Reports about government surveillance have shown there is a real need for greater disclosure and new limits on how governments collect information. The US government should take this opportunity to lead this reform effort and make things right."

Google CEO Larry Page described the security of users' data as "critical," adding that his company's efforts to protect this data with encryption have been "undermined by the apparent wholesale collection of data, in secret and without independent oversight, by many governments around the world."

Microsoft general counsel Brad Smith said: "People won't use technology they don't trust. Governments have put this trust at risk, and governments need to help restore it."

The Wikileaks Twitter account, widely understood to be used by its leader Julian Assange, was unconvinced as to why the technology companies have now spoken out about surveillance concerns.

"Google, Apple, Microsoft express concern about mass spying after seeing profit problems over their complicity in it," the account said.