He pointed to the case of a Saudi man, Khalid Ali-M Aldawsari, who was convicted last year of attempting to use a weapon of mass destruction.

WSJ: FBI Uses 'Tripwires' to Catch Bomb Makers

Among the recent examples cited by Boyd was the case of Saudi student Khalid Ali-M Aldawsari who was convicted and sentenced to life in 2012 for attempted use of a WMD.

CNN: WMD: From A-bombs to pressure cookers

Mr Naseer denies five counts, Mr Khalid four and Mr Ali three, all between Christmas Day 2010 and 19 September 2011.

BBC: Terror trial: 'Public duped into funding bomb plotters'

Irfan Naseer, 31, Irfan Khalid, 27, and Ashik Ali, 27, were convicted of being "central figures" in the plan which was foiled after months of surveillance work by police.

BBC: Birmingham terrorism threat 'remains high', police say

Mr Khalid, from Sparkbrook, faces four such charges and Mr Ali, from Balsall Heath, is accused of three.

BBC: Jury retires in terror trial of Birmingham men