Britain's ban on laptops and tablets being carried as cabin baggage on inbound flights from a group of Middle East countries could at some stage be extended to all flights, Home Secretary Amber Rudd has suggested.
It was announced on Tuesday that passengers will no longer be able to carry large electronic devices on inbound flights from Turkey, Lebanon, Jordan, Egypt, Tunisia and Saudi Arabia.
It will theoretically stop a terrorist on an affected flight from physically triggering a bomb concealed in a laptop and would ensure any explosion takes place in the hold, away from other passengers.
Ms Rudd said the ban was based on intelligence assessments but hinted that it could be extended, potentially affecting millions of travellers.
Asked why such devices were not banned from all flights if bombs can be hidden in them, Ms Rudd told BBC One's Andrew Marr Show: "It's difficult to say how far this will go, whether we may at some stage arrive at that place.
"But at the moment the Government has made the decision on where to have that ban in place based on intelligence we've received."
The move was ordered by Prime Minister Theresa May on Tuesday in the latest of a series of meetings on aviation security.
However, it was not immediately clear whether the move was introduced in response to a general terror threat or a specific plot from the likes of al Qaida.
It follows a similar measure announced on Tuesday by the US authorities affecting flights originating in a longer list of eight mainly Muslim countries.
UK airlines operating direct flights which are being hit by the new measures are British Airways, easyJet, Jet2.com, Monarch, Thomas Cook and Thomson.
Overseas airlines affected are Turkish Airlines, Pegasus Airways, Atlas-Global Airlines, Middle East Airlines, EgyptAir, Royal Jordanian, Tunis Air and Saudia.
The ban covers devices larger than a typical smartphone and means that all bigger gadgets, including Kindles and other e-readers, will have to go in the luggage holds of aircraft.
The restriction covers any electronic device measuring 16cm (6.3in) by 9.3cm (3.7in) by 1.5cm (0.6in).
This includes laptops, e-readers and tablets, as well as some gaming systems and large smartphones.