The background of the would-be suicide bomber who tried to blow himself up aboard an American Airlines jet appears to be very different to that of the perpetrators of the 11 September attacks on the United States.

Richard Reid - who was subdued by the crew and passengers - has now been identified as a British-born man who converted to Islam and seems to have been radicalised by people he may have met in the Muslim community in London.

But while his identity is now clear, the path that took him from small-time criminal to would-be suicide bomber remains unknown.

What is clear is that he is unlikely to have acted alone, nor would he have possessed the skills to manufacture the improvised explosive device that he tried to detonate on board Flight 63 from Paris to Miami.

Senior figures at the Brixton Mosque where he worshipped have claimed that they raised concerns about Mr Reid's behaviour some five years ago but that the British police did little.

This is a worrying development for the authorities.

Al-Qaeda links probed

Most of the individuals involved in the 11 September attacks on the US appear to have been Saudi or Egyptian nationals, albeit people who had spent some time in the United States.

No links have yet been established between Mr Reid and Osama Bin Laden's al-Qaeda network.

But the possibility that individuals among local Muslim communities in the West may have been recruited for terrorist acts gives this whole campaign an additional dimension.

It underscores once again the delicate balance that must be struck by the authorities in Britain and elsewhere.

On the one hand, they must clamp down on those seen as a threat, but they also must maintain due regard for the civil liberties of the majority of the population, whatever their religious beliefs or background.