The UK has announced a cabin baggage ban on laptops on direct 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 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.
