London, United Kingdom: Britain and the United States have announced bans on laptops and tablet computers from the cabin of flights from several Middle East and North African nations.

The restrictions are different in the two countries and only Britain has specified the maximum size of electronic device allowed -- 16 by 9.3 centimetres (6.3 by 3.7 inches).

Canadian and French officials are considering whether to impose similar measures, but Germany, Switzerland, Australia and New Zealand said they are not currently mulling a ban.

Here is what we know so far:

- Airports affected -

The US ban applies to flights from 10 airports in eight countries.

The airports affected are:

- Ataturk in Istanbul, Turkey 

- Cairo International in Egypt

- Dubai and Abu Dhabi in the United Arab Emirates

- Hamad International in Doha, Qatar  

- King Abdulaziz International in Jeddah, Saudi Arabia 

- King Khalid International in Riyadh, Saudi Arabia 

- Mohammed V International in Casablanca, Morocco

- Kuwait International

- Queen Alia International in Amman, Jordan

The British ban affects all the airports in six countries -- Egypt, Jordan, Lebanon, Saudi Arabia, Tunisia and Turkey.

- Banned devices -

Britain said it would be banning "phones, laptops or tablets larger than a normal-sized mobile or smartphone" from direct inbound flights from the countries named.

It specified that the ban would apply to devices bigger than 16 centimetres in length, 9.3 cm wide and 1.5 cm thick -- smaller than some e-readers like Kindles.

The United States said its ban applied to all electronic devices larger than an average-sized mobile phone, including game consoles.

- Affected airlines -

Since US airlines do not have direct flights from the airports affected, its ban affects nine non-US airlines: EgyptAir, Emirates and Etihad Airways, Kuwait Airways, Royal Air Maroc, Royal Jordanian, Qatar Airways, Saudi Airlines and Turkish Airlines.

The British ban affects six British airlines, including charters -- British Airways, EasyJet, Jet2.com, Monarch, Thomas Cook and Thomson.

It also impacts eight foreign carriers, including Egyptair, Royal Jordanian, Tunis Air and Turkish Airlines.

- Timing of bans -

Airlines in the United States have been given 96 hours, from 3:00 am (0700 GMT) on Tuesday, to inform travellers. Officials were not able to say when the order would end.

Britain said its ban must be implemented by 0001 GMT on Saturday, adding that passengers should act as if it has already come into effect.

Transport Secretary Chris Grayling said that while the government hopes the measure is temporary, it will "keep it in place for as long as necessary".

- Why impose bans? -

Officials in both Britain and the United States would not give any details on what exactly prompted the bans.

The US Department of Homeland Security, however, said extremists were seeking "innovative methods" to attack jets.

It cited an incident in Somalia in February last year in which the Shabaab insurgent group said it had managed to place a bomb in a plane leaving Mogadishu for Djibouti.

The device exploded shortly after takeoff, ripping a hole in the plane's side, but killed only the suspected bomber before the aircraft landed safely.

American authorities also cited the downing of a Russian airliner in Egypt in 2015, as well as attacks at airports in Brussels and Istanbul.

A government source in London only said Britain was "privy to the same intelligence" as the United States.

Grayling said: "We face a constantly evolving threat from terrorism and must respond accordingly."

CNN quoted a US official as saying the ban was believed to be related to a threat posed by Al-Qaeda in the Arabian Peninsula, known as AQAP.