Organised crime

It was not said how many people took part in Tuesday's raid, in which armed men opened fire on security staff before blasting the vault open with dynamite.

Eight guards were found in the bank's basement with their hands tied behind their backs, tape covering their mouths and each with a single bullet to the back of the head.

Police suspected the robbers got help from an inside source, as bank guards working on the overnight shifts were instructed not to open the doors for any senior officials.

Security officials believe there are links between organised crime in Iraq and the insurgency against US and Iraqi security forces.