The phone, internet and email records of ordinary UK citizens have reportedly been stored and analysed by America's National Security Agency, following a secret deal with the British Government made in 2007, according to The Guardian and Channel 4 News.

The claims are based on the latest documents to emerge from ex-CIA and NSA whistleblower Edward Snowden.

The Guardian says the agreement allowed the NSA to store previously restricted material on UK citizens not suspected of wrongdoing but incidentally caught up in surveillance operations. The newspaper calls it the first explicit confirmation that UK citizens have been caught up in US mass surveillance programmes.

The reports come as the European Parliament's Civil Liberties Committee of MEPs continues its investigation into claims of mass electronic surveillance on UK and European citizens by the NSA and Britain's GCHQ, and is bound to strengthen MEPs' efforts to protect the privacy of personal data.

The fallout from the claims have already led the Brussels-based Committee to strengthen a draft pan-European data protection law which is likely to be ratified next year. And it has led to EC moves to develop a secure, Europe-wide cloud computing industry which is not tarnished with the suspicion surrounding US-based cloud service providers.

The Guardian says that: “In 2007, the rules were changed to allow the NSA to analyse and retain any British citizens' mobile phone and fax numbers, emails and IP addresses swept up by its dragnet. Previously, this data had been stripped out of NSA databases – ‘minimised', in intelligence agency parlance – under rules agreed between the two countries.”

The newspaper alleges that this secret deal changed the so-called ‘Five Eyes' agreement, established at the end of the Second World War, which covered intelligence-sharing between the UK, US, Australia, New Zealand and Canada. “Until now, it had been generally understood that the citizens of each country were protected from surveillance by any of the others,” the newspaper said.

This point was highlighted by Caspar Bowden, an independent privacy researcher and a former chief privacy adviser to Microsoft, who previously appeared before the European Parliament's Civil Liberties Committee enquiry.

Bowden told SCMagazineUK.com: "This document shows the NSA planning to spy on the UK unilaterally, and confirms that the UK-USA agreement dating from World War II was never a 'no-spy' treaty and was never formalised into one. This possibility was raised in my briefing to the European Parliament inquiry into mass surveillance, and there should now be a full public inquiry in the UK."

The Guardian said that GCHQ and the Cabinet Office have declined to comment on its claims.