US defends spying on websurfers

The US National Security Agency has asked for a criminal investigation into how highly classified information about its secret surveillance of internet users was leaked.

US officials have acknowledged that a data-harvesting programme called Prism exists, but Google, Facebook and Yahoo! denied at the weekend that they had allowed access to their servers through Prism.

In the UK, Foreign Secretary William Haig said law-abiding Britons had "nothing to fear" from state surveillance, as he sought to calm concerns over the US government's secret monitoring of internet users.

However, he declined to say what Britain knew about the surveillance tools of the US, its closest intelligence partner.

Hague said: "Intelligence-gathering in this country is governed by a very strong legal framework, so that we get the balance right between the liberties and the privacy of people and the security of thecountry."

James Clapper, US National Intelligence director, said Prism had been mischaracterised by the media.

He said the project is legal, is not aimed at US citizens and has thwarted threats against the country. His office confirmed that "a crimes report" had been filed in connection with the leaking of information about Prism.

Clapper said: "Over the last week we have seen reckless disclosures of intelligence community measures used to keep Americans safe."

The news reports had slides showing how major internet companies such as Yahoo!, Google, Facebook and a half-dozen others were involved.

Clapper said that Prism was only used against specific individuals living abroad, not US residents.

At the weekend, President Barack Obama confronted his Chinese counterpart Xi Jinping over "cyber espionage" .

The Washington Post recently reported that cyber attacks from China had accessed data from dozens of Pentagon weapons programmes.

The leaders held eight hours of talks over two days.

According to US National Security Adviser Tom Donilon, Obama told Xi that if "direct theft of US property" emanating from China continued it would be "an inhibitor to the relationship". Chinese officials said after the summit that Xi opposed all forms of cyber spying.