No one, none of the sources the OP has shown, claims that Libya has a dirty bomb. As for components being nuclear weapons... only in the same sense that a pile of car parts laying in a heap on my front lawn is a car.
As stated in my previous post, the claim by the Prime Minister was "nuclear weapons", but the exact nature was not specified. It could be anything from Soviet loose nukes bought from the Russian Mob to a pound of Cesium-137 extracted from old dental X-ray machines.
Your car analogy doesn't fly since nuclear material, all by itself, is dangerous just as a pound of High Explosive is dangerous even if it isn't assembled into a time bomb with a detonator, battery and a timer.