Until this week, the revelations published by the Guardian about the nature and extent of internet surveillance had provoked little reaction from British politicians. The quality of the debate in the US provides an unflattering contrast to the muted debate this side of the Atlantic.

Some of the revelations have described far-reaching intelligence-gathering capabilities. There are questions of principle here that require answers. Are such capabilities necessary and proportionate? Does the benefit to national security clearly outweigh the infringement of privacy? Are there proper checks and balances to guard against abuse? To ask these questions is not to question the good faith of those who work for the agencies. I have had the privilege of working with all three security services, and have nothing but praise for their professionalism.

I don't doubt that they comply with the legal framework set for them by parliament. The issue is whether the rules we have set are fit for the internet age.

The Regulation of Investigatory Powers Act (Ripa), which regulates the powers of public bodies to carry out surveillance and investigation, was drafted 15 years ago, before the internet revolution had taken hold. There was no Facebook, no Twitter, no Skype. Google was still being run out of a garage. The way we use the internet, and the scale of the data we generate, has changed beyond recognition since then. In 2013, it took the world 10 minutes to generate the same amount of information that was created in the whole period from the dawn of history to 2002.

The agencies have harnessed the power of new technologies to ensure that we keep pace with criminals and terrorists. That is entirely right – I would expect them to do so. The question is whether the development of these new capabilities is proportionate and held properly accountable.

There are two obvious problems. First, our current legal framework allows GCHQ to collect data from "external communications" in bulk. The volume of that data, and the insight it can give into people's private lives, has increased exponentially since the early days of Ripa. At the same time, the distinction between domestic and external communications has become blurred, with the result that GCHQ may capture UK to UK as well as international traffic.

I'm delighted that the Royal United Services Institute has agreed to convene an Obama-style review to examine these kinds of questions, led by a panel of experts with backgrounds in technology, civil liberties, and intelligence work. It will report back after the general election. I hope that we can construct a cross-party consensus around their recommendations, and those of the similar inquiry by the intelligence and security committee.

Second, the agencies operate in the public interest, but the public interest cannot be democratically determined behind closed doors. It is not enough for the agencies to claim that they strike the correct balance between privacy and national security: they must be seen to do so. That means greater transparency, and strong, exacting, third-party oversight.

I believe the following steps, which together represent a significant revamp of the oversight applied to our intelligence agencies, should be introduced as quickly as possible: annual transparency reports detailing the requests for data which government makes from internet service providers and telecoms firms; and a new web portal (which could be www.surveillance.gov.uk) to act as a single source of information about the work of the agencies.

The intelligence and security committee needs reform – it is widely seen as being too deferential to the bodies it scrutinises. The coalition has recently given the committee more powers and resources, but we should go further. The membership of the committee should be expanded from nine to 11, to match the standard size of select committees.

The chair should in future be an opposition party member, to avoid accusations that the committee is too cosy with the government of the day. Hearings should be held wherever possible in public. Budgets should be set for five years ahead, to allow it the stability to plan a long-term work programme.

Changes should also be made to the Investigatory Powers Tribunal, which considers complaints against the use of intrusive powers by the intelligence agencies and others. There is currently no right of appeal – if the tribunal rules against an individual, his or her only recourse is to the European court of human rights. We should enable appeals to be heard in this country, and publish the reasons for rulings.

Finally, we should create an inspector general for the UK intelligence services, with reinforced powers, remit and resources. This would bring together two existing offices, the interception of communications commissioner, and the intelligence services commissioner.

I have not yet been able to agree these ideas within government with my coalition partners but I believe they are important and much-needed reforms. The Liberal Democrats will continue to champion their introduction both inside and outside of government and I hope that both the Conservative and Labour parties will support them sooner rather than later.

It is in all our interests that the intelligence agencies are able to operate successfully. Their effectiveness, and ultimately our own safety, depends on their ability to command public trust. The framework under which they operate must therefore be debated in public, reflecting technology as it is today, and striking the right balance between privacy and security.

