William Hague told the Commons the changing nature of terrorist threats had only increased the importance of Britain's intelligence relationship with the US. But the Foreign Secretary dismissed accusations that GCHQ had used its relationship with the United States to get around UK law.
Addressing the Commons this afternoon, the Foreign Secretary William Hague said the Government took great care to balance individual privacy with a duty to safeguard security.
The Government deplores the leaking of any classified information wherever it occurs. Such leaks can make the security of our own country and that of our allies more difficult.
The House will understand I will not be drawn in to confirming or denying any aspect of leaked information.
To intercept the content of any individual's communications in the UK requires a warrant signed by me, the Home Secretary or another Secretary of State. This is no casual process.
Prime Minister David Camerson said Britain's security agencies operated within the law and were subject to "proper scrutiny."
Foreign Secretary William Hague will address the House of Commons later amidst accusations Britain's GCHQ was involved in the NSA surveillance programmes.
Deputy Political Editor Chris Ship reports.
Prime Minister David Cameron stressed UK intelligence agencies operated within the law and were subject to "proper scrutiny" by politicians.
Speaking to ITV News Political Correspondent Libby Wiener Mr Cameron said the UK's intelligence services were necessary to protect citizens in a "dangerous world".
David Cameron's spokesman said the Prime Minister believes GCHQ operates within UK law, and that it was "fanciful" to think the agency would be trying to work out how to circumvent its legal framework. Speaking to reporters he said:
I think the PM's view is that the agencies operate within this framework and as the Foreign Secretary said the idea that in GCHQ people are sitting working out how to circumvent a UK law with another agency in another country is fanciful.
He thinks that the necessary and important frameworks are in place and that there has been a lot of questions that have been raised and the right thing to do is for the Foreign Secretary to go to the House and give a statement.
Tory Sir Malcolm Rifkind, chairman of the committee of MPs and peers which overseas the work of security services said GCHQ would need authority for any request to monitor emails of a UK citizen, even if it was carried out by US agencies. Speaking to BBC Radio 4's Today programme, he said:
One of the big questions that's being asked is if British intelligence agencies want to seek to know the content of emails, can they get round the normal law in the UK by simply asking an American agency to provide that information?
The law is actually quite clear: if the British intelligence agencies are seeking to know the content of emails by people living in the UK, then they actually have to get lawful authority. Normally that means ministerial authority.
It requires ministerial authority or authority from the relevant senior person. It cannot simply be done by the agencies making their own decision about whose mail they are going to intercept or telephone calls they are going to intercept.
William Hague will face questions from MPs today over GCHQ's links to a controversial US internet monitoring programme.
The Foreign Secretary is due to make a statement to the Commons amid mounting pressure to reveal information about connections to the Prism system.
Speaking on the BBC's Andrew Marr Show yesterday, Mr Hague insisted the British eavesdropping agency had not been trying to dodge tough legal checks on their activities.
The law-abiding British public had "nothing to fear" from their work, he added.
Mr Hague said: "As someone who knows GCHQ very well... the idea that in GCHQ people are sitting working out how to circumvent a UK law with another agency in another country is fanciful. It is nonsense."
The Cabinet minister declined to confirm that he had personally authorised engagement with the US Prism programme.
Business Secretary Vince Cable said today that it was a possibility that the Prism system may have allowed the Government to operate a covert sort of snoopers' charter, after the Foreign Secretary claimed that GCHQ did not try to dodge tough legal checks on their activities.
Mr Cable told Sky News' Murnaghan programme: "One is that the Americans have developed this very sophisticated Prism system, which enables them to get access to data in other countries, with or without our knowledge.
"And there is a separate issue about whether GCHQ were involved in some collaborative exercise.
"I think a lot of people will be reassured that we do work well with the Americans, but the whole point about surveillance is you have got to have it when you're dealing with terrorism or other crimes".