The threat has been taken so seriously it came close to leading to an outright ban on all hand luggage, a senior insider has revealed.
Mobile phones and electronic devices could still be banned from plane cabins, with the threat of a 9/11-style coordinated attack on London and other major cities feared imminent.
The warning comes as Whitehall officials admit that a terror strike on the UK is now “almost inevitable” particularly with British jihadis returning from fighting alongside the Islamic State in Iraq and Syria.
An airport security source told the Sunday Express: “We’ve been told that five planes are being targeted in a high profile hit before Christmas. They’ve been waiting for the big one.
“We have many scares but this one nearly got hand baggage pulled from all airlines. The threat is still alive and real.”
The plot, which has been known about for the past two months, is thought to involve Islamists smuggling bombs on to planes bound for major European destinations before Christmas.
The well-placed security insider said talks had been held about how to deal with it, with suggestions made to ban hand luggage.
The source said: “High level negotiations are continuing at Governmental level but at the moment there has been little done to respond.
“There is paralysis because of the difficulty of banning hand luggage which is one of the strongest weapons we have against the new threats.
“All electronics may be banned from hand luggage and placed in the hold, that has been considered, and there has been behaviour analysis training at airports but while it’s effective, it’s difficult to roll out quickly and is not a sufficient safety net.
“The threat is aimed at Europe. The U.S has improved their security over the summer but we have not.
“Everyone is expecting something catastrophic very soon”.
Threats of bombs hidden in toothpaste tubes caused huge disruption to travellers to the Sochi Winter Olympics and stringent security checks at UK airports will cause huge queues during what is the busiest time of the year for airlines.
Security experts also warn that future terror attacks could be carried out by sleepers – western converts as likely to have blond hair and blue eyes as dark skin and beards.
The latest threat is understood to have been uncovered by American intelligence officers who fear that despite success in taking out key Al Qaeda bomb-makers, the genie is out of the bottle and sleeper cells are currently preparing for a doomsday scenario.
David Drugeon, a 24-year-old Frenchman and one of Al Qaeda’s most trusted bomb-makers was killed by a cruise missile strike earlier this month to the west of the Alepo, Syria.
Drugeon, who was part of an Al Qaeda off-shoot called the the Khorasan group, and was said to be targeting US and UK airlines with non-metallic explosive devices, which could be concealed in mobile phones, computers and printer cartridges.
Although now dead his work remains a huge threat as his skill set is likely to have been spread among a number of terror apprentices, including an unidentified Saudi-born bombmaker.
Last night leading terrorism expert Dr Sally Leivesley said the banning of hand luggage and hand held electronic devices is unlikely to be accepted by the airlines despite the risks.