The UK has announced a cabin baggage ban on laptops on passenger flights from Turkey, Lebanon, Jordan, Egypt, Tunisia and Saudi Arabia.
The restrictions, which also apply to tablets, DVD players and phones over a certain size, follow a similar US ban affecting eight countries.
Downing Street said they followed talks on air security and were “necessary, effective and proportionate”.
US officials said bombs could be hidden in a series of devices.
The six affected UK carriers are:
- British Airways
- Thomas Cook
The eight overseas airlines subject to the ban are:
- Turkish Airlines
- Pegasus Airways
- Atlas-Global Airlines
- Middle East Airlines
- Royal Jordanian,
- Tunis Air
The ban applies to any device, including mobiles and smart phones, larger than 16cm long, 9.3cm wide or 1.5cm deep.
Any affected device will need to be placed into hold luggage and checked in before passengers go through airport security.
A UK government spokesperson said: “Decisions to make changes to our aviation security regime are never taken lightly.
“We will not hesitate to act in order to maintain the safety of the travelling public and we will work closely with our international partners to minimise any disruption these new measures may cause.”
The US ban applies to flights on nine airlines from 10 airports in eight countries.
What are the new US rules?
The BBC home affairs correspondent Daniel Sandford says the move was “obviously part of co-ordinated action with the US”.
The attempted downing of an airliner in Somalia last year was linked to a laptop device, and it appears the security precautions are an attempt to stop similar incidents, our correspondent added.
The US has given airlines 96 hours, beginning at 07:00 GMT on Tuesday, to implement the ban, which officials said had no end date.
Passengers on some 50 flights a day from some of the busiest hubs in the Middle East, Turkey and North Africa will be affected.
The Turkish government has said the US ban is wrong and should be reversed.
But the Department of Homeland Security said extremists were seeking “innovative methods” to bring down jets.
In a statement, it said the US government was “concerned about terrorists’ ongoing interest in targeting commercial aviation, including transportation hubs over the past two years”.
Citing the Somalia incident in February 2016, as well as the 2015 downing of a Russian airline in Egypt and attacks at airports in Brussels and Istanbul, it added: “Evaluated intelligence indicates that terrorist groups continue to target commercial aviation, to include smuggling explosive devices in various consumer items.”