EL MUNDO tells something about that the hexogen detected is a component of RDX or Semtex that could have been purchased in Eastern Europe before the so called "truce".
ETA has an effective supplying network that from Southern France reaches the Balkans and Eastern Europe, and in occasions they contact Middle East groups.
Regards,
J Aguilar
The old eastern block manufactured Cemtex - a Soviet version of C-4 (at least something like it). Known as a plastique, the material is commonly used by terrorist networks, and Soviet made explosive devices - Like the American PETN, which is virtually everywhere as a propellant and an explosive.
SS