BBC News with Jonathan Wheatley

The man who led Britain into war in Afghanistan and Iraq, Tony Blair, has described radical Islam as the greatest threat facing the world. In a BBC World Service interview, the former British prime minister said radical Islamists - whether in

Chechnya, Kashmir, the Palestinian territories, Iraq or Afghanistan - believed that anything done in the name of their cause was justified.

"After September 11th, rightly or wrongly, I felt the calculus of risk had changed, and I feel it's still changed. I still think there is the most enormous threat from the combination of this radical extreme movement and the fact that if they could, they would use nuclear, chemical or biological weapons. I think they would if they could, and I think you can't take a risk with that happening."