PM: Bomb designed to blow up plane

An explosive device found hidden in a printer cartridge on a cargo plane at a UK airport was apparently designed to blow the aircraft out of the sky, David Cameron said.

Mr Cameron was speaking as Yemeni officials arrested a woman on suspicion of sending the two mail bombs, found on Friday in cargo hubs at East Midlands Airport and in Dubai, sparking an international terror alert.

The packages originated in Yemen, a key front in the fight against terrorism, and are believed to have contained the powerful explosive PETN.

Mr Cameron said: "We believe that the device was designed to go off on the aeroplane. We cannot be sure about the timing when that was mean to take place. There is no early evidence it was designed to take place over British soil, but of course we cannot rule that out."

Speaking at Chequers ahead of a meeting with German Chancellor Angela Merkel, he confirmed he had spoken to US president Barack Obama, adding: "I have also spoken to President Saleh of the Yemen making the point that we have to do even more to crack down and cut out the cancer of al Qaida in Yemen and the Arabian Peninsula.

"We have immediately banned packages coming to or through Britain from the Yemen and we will be looking extremely carefully at any further steps we have to take.

"In the end these terrorists think that our interconnectedness, our openness as modern countries is what makes us weak. They are wrong - it is a source of our strength, and we will use that strength, that determination, that power and that solidarity to defeat them."

He said the package started in Yemen, landed in Germany and was then transported to Britain en route to America, adding: "It just shows how united and determined we have to be to defeat terrorism."

Yemeni officials said they were hunting a number of suspects who are believed to have been using forged documents and ID cards and to be linked to group al Qaida in the Arabian Peninsula (AQAP).

Yemeni President Ali Abdullah Saleh said security forces surrounded a house where the woman was hiding after receiving intelligence from the US and United Arab Emirates.