The bomb was found in a printer cartridge on a plane in a UK airport, after being posted from Yemen.

A second printer bomb, also sent from Yemen, was intercepted in Dubai.

The bombs were both addressed to synagogues in the US city of Chicago, and were claimed by al-Qaeda in the Arabian Peninsula (AQAP).

The UK bomb, intercepted at East Midlands airport, was discovered early on 29 October, following a tip-off from Saudi intelligence.

It was removed and "disrupted" by explosives officers about three hours before it was timed to detonate, British police said in a statement.

The White House said the findings "underscore the serious nature of the attempted AQAP attack and the challenge we all face in trying to prevent or disrupt such attacks".

Spokesman Nicholas Shapiro thanked the UK authorities for the "highly professional nature" of their investigation, and said the US would continue to work closely with London - as well as with Saudi Arabia, United Arab Emirates and Yemen - to counter the threat posed by AQAP.

Last week, French Interior Minister Brice Hortefeux said one of the two bombs had been 17 minutes from detonating when it was discovered - he did not specify to which device he was referring.