The interception of two explosive packages en route from Yemen to the US has sparked a global terror alert.
Yemeni security forces have already launched a clamp down across the capital Sanaa with dozens of check points reportedly being set up.
US President Barack Obama has described the suspected bomb plot as credible after the parcels were found on separate cargo planes in the UK and Dubai.
The potentially deadly packages, which were disguised as ink cartridges, were both bound for two synagogues in Chicago.
For the moment, the British government has not confirmed whether the devices would have worked.
Britain’s Home Secretary Theresa May said: ‘‘The suspect package originated in Yemen. It was removed fro examination by forensic experts. I can say at this stage that it did contain explosive material but it is not yet clear whether it was a viable explosive device.’‘
Suspicion has fallen on al Qaeda, which has affiliates operating in and out of Yemen.
Only last Christmas, the group claimed responsibility for a failed bomb plot to blow up a plane as it was landing in the American city of Detroit.