Leading article: The need to scrutinise our intelligence services

The police and intelligence operation to track down the would-be suicide bombers of 21 July appears to have been impressive. Surveillance technology was used to good effect. And, crucially, the fugitives were taken alive. Now our security services have a potentially valuable source of information on the nature of the threat facing Britain. But this success should not prevent us from asking hard questions about the quality of our intelligence and security services. When Parliament returns from the summer recess, the Government should establish an independent public inquiry to examine our domestic intelligence apparatus.

Britain invests heavily in its intelligence resources. Yet the threat posed by British-born militants appears to have been missed. In the lead-up to the 7 July bombings, the UK shifted to a lower level of alert. Intelligence officials briefed that no group had the capacity to attack Britain. That, as the Home Secretary admits, was a failure of intelligence. One of the London bombers, Mohammad Sidique Khan, was investigated by MI5 last year, but deemed not to be a threat. This suggests that, contrary to initial briefings, the first wave of London bombers were not all "clean skins". As with the second wave, our security services seem to have failed at their primary job.

The debacle over Iraq's weapons of mass destruction underlines the need for a thorough investigation. We now know that Saddam Hussein had no stockpiles of chemical, biological or nuclear weapons. That did not stop the intelligence community colluding in the Government's assertion that Saddam's armoury posed an imminent threat. This error was not, of course, confined to Britain. But the evidence that emerged at the Hutton and Butler inquiries revealed the extreme limitations of our intelligence gathering in the Middle East, with over-reliance on limited and partisan sources.

It is vital to the security of this country that we ask hard questions about the intelligence services to ensure they are as effective as possible. Have they fully woken up to the fact that the Cold War is over and that the most pressing threat to our society is Islamic terror organisations? Are they concentrating on the right targets? Do they have the right tools to do the job, in terms of human, electronic and financial resources?

Any inquiry should follow the example set by the 911 Commission, set up to examine the performance of the US intelligence services in before the 2001 attacks on New York and Washington. This thorough and non-partisan report revealed that various agencies failed to share information and often engaged in bureaucratic competition. Its recommendations have resulted in a major reforms.

British intelligence services hide behind a veil of secrecy. This in unhealthy in a democracy, especially one facing our current challenges. It is true that Britain's intelligence services already have to answer to Parliament's Intelligence and Security Committee. But the ability of this collection of MPs to scrutinise is limited. For one thing, they have only five full-time staff. This does not compare well with the 500 at the disposal of US Congressional committees or the Inspector General of the CIA. And such is the magnitude of the events of the past month that a more fundamental - and open - investigation is needed.

We should be careful not to pre-empt an inquiry. There may be good reasons why the bombers slipped through the security net. And it is impossible for the intelligence community to make public all sources of information. Secrecy matters. But as America has shown, democratic scrutiny is a virtue - even in an area as sensitive as espionage and intelligence gathering.