Jonathan Corbett said he had been told by a commercial aviation security official that it was suspected that the theft, a few months ago, had been carried out by members of ISIS in order to examine how they could conceal an explosive in such a way that it could not be detected.

He pointed to the fact that a laptop exploded at an airport security checkpoint in Somalia on 6 March and said it appeared that the US Department of Homeland Security had come to the conclusion that the theft and the explosion were related.

The ban on carrying anything larger than a mobile phone on one's person while flying came into force in March. The US move was promptly followed by the UK, but the two countries banned a differing list of airlines, with the latter including some British carriers as well.

The airports hit by the US ban are: Queen Alia International Airport (Jordan), Cairo International Airport (Egypt), Ataturk International Airport (Turkey), King Abdul-Aziz International Airport (Saudi Arabia), King Khalid International Airport (Saudi Arabia), Kuwait International Airport, Mohammed V Airport (Morocco), Hamad International Airport (Qatar), Dubai International Airport (United Arab Emirates) and Abu Dhabi International Airport (United Arab Emirates).

The UK ban affects Middle Eastern carriers Royal Jordanian Airlines, Egypt Air, Turkish Airlines, Saudi Arabian Airlines, Kuwait Airways , Royal Air Maroc, Qatar Airways, Emirates and Etihad Airways. British carrier affected are British Airways, EasyJet, Jet2.com, Monarch, Thomas Cook, Thomson. Foreign carriers affected are Pegasus Airways, Atlas-Global Airlines, Middle East Airlines, Tunis Air and Saudia.

Corbett wrote that there was some logic to the ban since lithium batters were opaque to X-rays and a metal box, which was the same size as a battery and filled with explosives, would look the same.

But, he said, there were problems with the approach. For one, anyone who planned to use a laptop to conceal a bomb would simply use something else once the ban was in place. Secondly, by forcing all the batteries (inside devices) to be stored in the hold, the chance of fires was increased.

And thirdly, he wrote, the ban was not economically viable as it meant the loss of millions of hours of productivity.

Corbett claimed the theft of the X-ray equipment had been kept quiet because it would upset the average "mom from the midwest planning to fly her kids to Disney" and drastically reduce the number of people flying.

He said that the classified information leaked to the Russians by US President Donald Trump recently was likely to have been "about how the government was able to infiltrate ISIS to investigate the use of the stolen x-ray machines".

"Most news organisations did not report the nature of Trump’s disclosure other than that it related to “a plot by Islamic State, although The Washington Post actually did describe it as laptop-ban related," he wrote.

"So at the same time as the American people are misled about the risks of flying, the Russians were given more information than the airlines and airport operators who are responsible for actually keeping bombs off of planes."