Hague: Law-abiding Britons have nothing to fear from GCHQ
"Law-abiding" citizens have "nothing to fear" from the British intelligence services, the foreign secretary says.
William Hague said reports that the UK's eavesdropping centre GCHQ had circumvented the law to gather data on British citizens were "nonsense".
But he refused to confirm or deny claims GCHQ has had access to a US spy programme called Prism since June 2010.
Mr Hague confirmed he would give a statement to Parliament on the allegations on Monday.
The existence of the Prism system was disclosed in reports by the Guardian and the Washington Post.
It is said to give America's National Security Agency (NSA) and the FBI easy access to the systems of nine of the world's top internet companies, including Google, Facebook, Microsoft, Apple, Yahoo and Skype.
All deny giving the US government access to their servers.
The UK government has come under pressure to respond to allegations that Prism has allowed GCHQ to circumvent the formal legal process for obtaining personal material such as emails, photographs and videos, from internet companies based outside the UK.
Speaking on BBC One's Andrew Marr show, the foreign secretary declined to say whether or not he had personally authorised GCHQ to engage with Prism.
But he said GCHQ's operations were subject to stringent legal checks and scrutiny.
'Oversight is strong'
He said: "That legal framework is strong, that ministerial oversight is strong.
"The net effect is that if you are a law-abiding citizen of this country going about your business and personal life, you have nothing to fear about the British state or intelligence agencies listening to the content of your phone calls or anything like that.
"Indeed you will never be aware of all the things that these agencies are doing to stop your identity being stolen or to stop a terrorist blowing you up tomorrow."
Mr Hague - the minister responsible for GCHQ - said it would "defeat the object" to reveal how GCHQ or the security services work, because it would help terrorist networks, criminal networks, and foreign intelligence agencies.
"If actually we could tell the whole world, or the whole country, how we do this business, I think people would be enormously reassured by it and they would see that the law-abiding citizen has nothing to be worried about," he said.
"But if we did that, it would defeat the object. This is secret work... it is secret for a reason."
GCHQ is to report to MPs over the allegations surrounding its access to Prism, with Parliament's Intelligence and Security Committee (ISC) expecting the report by Monday.
Lib Dem peer Lord Carlile, a former independent reviewer of terrorism legislation, defended the sharing of intelligence between the US and UK.
He told BBC Radio 5 live: "If the United States authorities acquire a piece of intelligence that may save lives in the United Kingdom, we would expect that intelligence to be shared whether it has been obtained under United States law, which may not be compatible with our own, or not."
Major General Jonathan Shaw, who was until last year head of cyber security at the Ministry of Defence, insisted that all public data was handled sensitively.
He told Sky News Murnaghan programme: "There is no such thing as total security, just as there's no such thing as total freedom.
"The public needs to really support the intelligence agency, and what we're seeing is an incredibly difficult job of getting the balance right between security and freedom."
Business Secretary Vince Cable told the same programme there were issues raised by the allegations that would have to be addressed and that surveillance should be "proportionate".
Both Google and Facebook have been among the companies to deny any complicity in the Prism system.
Google said the US government had no access, "not directly, or via a back door, or a so-called drop box".
The internet giant said it handed over only material demanded by court order under the US foreign intelligence surveillance act (FISA).
Facebook founder and CEO Mark Zuckerberg said: "Facebook is not and has never been part of any programme to give the US or any other government direct access to our servers."
The NSA has confirmed that it has filed a criminal report with the US Justice Department over the leaks that sparked the controversy.
Prism was reportedly established in 2007 under changes to US surveillance laws passed under President George Bush and renewed last year under Barack Obama in order to provide in-depth surveillance on live communications and stored information on foreigners overseas.
GCHQ, based at Cheltenham, is said to have generated 197 intelligence reports through the system in the 12 months to May 2012 - a 137% increase on the previous year.
GCHQ has refused to comment directly on the reports, but in a statement insisted it operated within a "strict legal and policy framework".