|No unaccompanied freight from Yemen will be allowed into the UK following the discovery of explosive material [AFP]
Britain is reviewing security measures after the discovery of what the home secretary called "a viable explosive device" at East Midlands Airport in Nottingham.
Speaking after a meeting of the government security committee Cobra on Saturday, Teresa May, the home secretary, said that no unaccompanied freight from Yemen would be allowed into the country.
The UK and Dubai, the commercial hub of the United Arab Emirates, intercepted two US-bound packages containing explosive material from Yemen on Friday.
"I can confirm the device was viable and could have exploded," May said.
"The target may have been an aircraft and had it detonated the aircraft could have been brought down."
The UK uses a system of accredited, trusted shippers which means some cargo is not screened or searched. Security may now be upgraded to mirror one hundred per cent screening in the US.
May said the threat level for "terrorist attacks" in the UK is at severe - the highest rating.
Cameron phone call
Against this backdrop, David Cameron, the British prime minister, spoke to Barack Obama to discuss the parcel-bomb plot.
A statement from the White House said the US president expressed his appreciation for the professionalism of American and British services involved in the joint effort to stop this plot and said that the two nations would continue to work together to prevent attacks.
Obama earlier said that although the culprits are unknown as yet, al-Qaeda in the Arabian Peninsula, a group based in Yemen, was known to plan attacks against the US and its allies.
Commenting on the bomb plot, Tobias Feakin of RUSI, a UK-based defence and security think-tank, told Al Jazeera: "We see this spectacular type of attack as an obsession for al-Qaeda operatives. However, targeting freight planes is new.
"Any security mechanism in the airline world is only as strong as the point of embarkation.
"So the weakness here is Yemen, where standards might not be as high as in the US or Europe. So it shows that there are no global standards."
The discovery of the suspicious packages in the UK and Dubai on Friday came after a tip from Saudi Arabia, the White House said, triggering a major security alert on three continents.
Officials scrambled to check other cargo bound for the US from Yemen.
The parcels were bound for two Jewish places of worship in the US city of Chicago, Obama said. Both contained computer printer equipment packed with powder and attached to wires.
One package, found in the UK, was on board a UPS cargo aircraft, while the other, in Dubai, was found in a FedEx sorting facility.
"International security co-operation has improved and appears to be working well at present," Feakin, the RUSI analyst, said.
However, he said that a kneejerk reaction to the incident, such as shutting down methods of physical economic transaction, should be avoided.
"That's what terrorism wants to do - to change the day-to-day operations of people," Feakin said.