The stream of revelations about the activities of Britain's intelligence agencies was “chipping away” at public support for their work, Nick Clegg has warned.

The Deputy Prime Minister was speaking after the disclosure that the Blair government gave the United States permission to store and analyse the email, mobile phone and internet records of potentially millions of Britons.

It also emerged that America security officials drew up plans to spy on UK citizens unilaterally, without the knowledge of the British government.

Download the new Independent Premium app Sharing the full story, not just the headlines

Earlier this month The Independent highlighted concerns that a covert listening-post was operating from the roof of the British embassy in Berlin.

Mr Clegg said proper accountability of the intelligence services, as well as checks they used their eavesdropping powers proportionately, were essential to increase public confidence in them.

He said that was important “because of course, with each passing day, with all of these revelations, you chip away at the bedrock of public support for the work of the agencies and that is a dangerous thing”.

The Deputy Prime Minister conceded the system of oversight for the intelligence services was “quite opaque” and signalled he was sympathetic to a wide-ranging inquiry into their activities and powers.

“I have an open mind about how you try and capture all these different issues to make sure we keep up with this revolution in the power of these information technologies which are now available to our intelligence agencies and also, of course, are available to people who want to do us harm,” he said.

Speaking on his weekly LBC 97.3 phone-in show, Mr Clegg paid tribute to the diligence and professionalism of the security agencies .

He added: “It is also clear the technologies which are now used by our security agencies are far, far more powerful and are able to store and analyse data on a scale we've never known before. We've simply never known before the ability now to hoover up, analyse, discard, process information is now on a scale which was unimaginable just even a few years ago.”