How much more arrogant can the Government get?

With reports that at least one MP - Sadiq Khan, who represents Tooting - has been bugged by counterterrorism police, this question has come under fresh scrutiny. According to the officer who placed the bug, Mr Khan was specifically targeted following pressure from the Metropolitan Police - raising questions that the Metropolitan Police Commissioner and Home Secretary must quickly account for.

The most worrying feature of the Khan case is the cavalier way in which the rules were broken and the casual nature of the Government's response. It is alleged that two conversations between Mr Khan and a constituent were bugged during 2005 and 2006. The constituent, Babar Ahmad, is in prison facing extradition to the US on terror charges.

There is no evidence of authorisation for the bugging, within police ranks or at ministerial level, which highlights a worrying lack of accountability in the exercise of such intrusive powers. It took more than two years for this breach of the rules to come to light - and it was revealed in the Sunday press rather than as a result of any checks in the system.

At stake is the Wilson Doctrine, a 40-year-old rule of Parliament that bars the bugging of MPs' phones. It is based on the importance of MPs being able to communicate freely with the public, coupled with a natural concern about the over-weening power of the state. It is based on the same principle that protects other relationships - such as the integrity of conversations people have with their doctors or lawyers. The Government has accepted that this bugging operation went against the principle and the spirit of the Wilson Doctrine.

People who come to their MP with a problem may be in trouble, distressed or scared. They may be whistle-bowers, seeking to disclose sensitive information of wider public interest. The Government has a track record of pursuing whistle- blowers, such as Derek Pasquill, the civil servant who revealed the Government's cosying up to radical Islamic extremists. It is vital to preserve a safe and secure avenue to air such legitimate concerns.

Some have argued against the Wilson Doctrine in its current form. We face a serious terrorist threat from Al Qaeda, and why shouldn't the same rules on bugging apply equally to politicians as to other people in this country? After all, we have had terrorist supporters elected to the House of Commons in recent history. There is no reason to rule out the possibility that it might happen again. It is always open to the Prime Minister to make the case - to Parliament and the public - for a change in the rules. But he must do it in an open, honest and accountable way. Earlier this year, Gordon Brown confirmed that he wanted to keep the rules as they were.

More broadly, the Khan case smacks of the slapdash way in which the Government treats accountability and transparency. Ministers said they became aware of this episode only last Saturday. Yet I wrote to the Prime Minister on 11 December 2007, highlighting concerns about this case. No 10 says it has no record of the letter. Ministers often take weeks if not months to respond to correspondence, but this is the first time I can remember a Prime Minister's office actually losing a letter. It is a mark of incompetence that when No 10 listed those letters it had received from me, it mistakenly said I had written to the PM on Licensing Laws. So much for its competence in handling correspondence.

When ministers finally cottoned on to the breach of the rules at the weekend, the response was lethargic. Yesterday's statement by Jack Straw, the Justice Secretary, more than two years on, left us none the wiser. Jack Straw is not the minister responsible for the police or security matters - the Home Secretary is. So it is hardly surprising that Mr Straw could not answer a single fact about the case - whether Mr Khan had been bugged, how such a breach could have been undetected for so long and whether any other MPs have been subject to surveillance.

Meanwhile the inquiry he announced is being led by the same civil servant who was tasked with preventing the breaches happening in the first place. So much for a rigorous and independent review.

In fact, Mr Straw's own department has now admitted that it knew about the alleged bugging of Mr Khan in - coincidentally - December. So did the Home Office. Both departments claim they did not tell ministers, let alone No 10, about these breaches of the Prime Minister's promise to Parliament. It is extraordinary that Mr Straw did not explain any of this to the House of Commons yesterday.

The whole episode displays an arrogant approach to the exercise of the powers of state - and lack of interest in proper transparency and accountability. But this is not an isolated instance. It reflects a broader trend under Labour.

The Information Commissioner has warned that we are sleepwalking into a surveillance society. The Government has accumulated broad powers over its citizens in a haphazard and unchecked manner. We have more CCTV cameras than any other country, the largest DNA database in the world and the prospect of ID cards to come - all without a clear focus or proper system of accountability to ensure safeguards and avoid abuse.

We have got to take security seriously, but security must come with accountability. Large Labour majorities in Parliament have rubber-stamped the increase of police powers in the name of security. It is ironic that the expansion of the surveillance state has now come back to haunt MPs. They might do well to consider that next time the Government proposes yet more unchecked powers in the name of security.