The US-UK ban on selected electronic devices from the passenger cabins of flights from some countries in north Africa and the Middle East was partly prompted by a previously undisclosed plot involving explosives hidden in a fake iPad, according to a security source.

The UK ban on tablets, laptops, games consoles and other devices larger than a mobile phone came into effect on Saturday. It applies to inbound flights from six countries – Egypt, Jordan, Lebanon, Saudi Arabia, Tunisia and Turkey. Six UK airlines – British Airways, EasyJet, Jet2, Monarch, Thomas Cook and Thomson – and eight foreign carriers are affected.

It follows a similar move in the US, which applies to flights from 10 airports in eight countries – Jordan, Egypt, Turkey, Saudi Arabia, Morocco, Qatar, Kuwait and the United Arab Emirates.

The security source said both bans were not the result of a single specific incident but a combination of factors.

One of those, according to the source, was the discovery of a plot to bring down a plane with explosives hidden in a fake iPad that appeared as good as the real thing. Other details of the plot, such as the date, the country involved and the group behind it, remain secret.

Discovery of the plot confirmed the fears of the intelligence agencies that Islamist groups had found a novel way to smuggle explosives into the cabin area in carry-on luggage after failed attempts with shoe bombs and explosives hidden in underwear. An explosion in a cabin (where a terrorist can position the explosive against a door or window) can have much more impact than one in the hold (where the terrorist has no control over the position of the explosive, which could be in the middle of luggage, away from the skin of the aircraft), given passengers and crew could be sucked out of any subsequent hole.

The UK ban was announced last week after a security meeting chaired by Theresa May, with the Department for Transport setting Saturday as the deadline for compliance. While the US also has a ban, countries in Europe, including Germany, have so far failed to follow suit.

The US Department of Homeland Security said the ban on selected electronic devices was partly the result of terrorists seeking “innovative methods” to attack planes.

While such fears are realistic – given a bomb suspected to have been hidden in a laptop on a flight in Somalia last year blew a hole in the passenger cabin – questions are being raised over whether the timing of the announcement by Donald Trump’s administration last week was out of frustration at the failure to implement his travel ban.

One of the oddities is that the US and UK bans, while overlapping in terms of some countries, have different lists.

Raffaello Pantucci, director of international security services at London’s Royal United Services Institute (RUSI), suggested the fact that others were not joining the US-UK ban pointed to a threat from al-Qaida in the Arabian Peninsula (AQAP), which has never abandoned its desire for “spectaculars”, rather than the relatively unsophisticated attacks encouraged by Islamic State, such as the one in Westminster last week. AQAP’s chief bombmaker, Ibrahim al-Asiri, has long been targeting the US and UK.

The US alleges that Saudi-born Asiri, 34, who was based in Yemen, was behind the failed Christmas Day attempt in 2009 to bring down a Detroit-bound plane by a suicide bomber with plastic explosives sewn into his underwear.

Shashank Joshi, a defence and intelligence specialist also at RUSI, said: “I understand why a tablet-sized, non-metallic bomb might pose a serious threat, given AQAP’s long-established expertise in this area. What confuses me is the scope of the ban.

“One problem is that the British and American restrictions differ, despite the exceptionally high level of intelligence-sharing between the two on AQAP and on counter-terrorism generally. Other western and western-allied countries have not undertaken the ban at all. This raises questions about why they have arrived at different conclusions, and specifically suspicions as to whether unstated political factors may be influencing the Trump administration.”

Joshi said that, whatever his suspicions of the Trump administration, he did not believe UK officials “would have imposed a ban without well-considered reasons of their own”.

Both the US and the UK send officials to airports around the world to check on security standards. Their assessments are based on whether terrorist groups are operating in the countries involved or have easy access to them, and whether airport security in those countries is vulnerable.

Security in Egypt had been regarded as vulnerable even before a terrorist bomb brought down a Russian passenger plane that took off from the Red Sea resort of Sharm el-Sheikh in October 2015 bound for St Petersburg. Although the Saudi government spends heavily on internal security, its airport security is regarded by the UK as failing to meet the necessary standards. The same assessment is made of Turkey.

One difference between the US and UK lists applies to Qatar and the UAE, which are not on the UK list. The UK assesses both as having high levels of airport security.

France is considering a ban but has still to take a decision. A spokesperson for the Dutch government said: “We are constantly monitoring the situation. At the moment we don’t see reasons to introduce similar measures.”

Belgium said it would not introduce a ban without a decision from the European Aviation Safety Agency, the EU body that develops pan-European safety rules. Australia said it would minotor the new arrangement but was not at present planning to follow suit.