All air passengers flying into or out of UK airports must ensure their electronic devices are charged, following updated guidance from the Department for Transport (DfT).

Advice issued at the weekend concerned passengers flying to the United States, but last night that instruction was widened to affect anyone flying into or out of the UK.

A spokesman for DfT said: "In line with the US advice, passengers on some routes into and out of the UK may now also be required to show that electronic devices in their hand luggage are powered up or face not being allowed to bring the device onto the aircraft.

"Passengers flying into or out of the UK are therefore advised to make sure electronic devices being carried in their hand luggage are charged before they travel."

No specific routes have been highlighted, and the spokesman said they hope to " minimise disruption as far as possible".

New restrictions requiring all electronic devices, including mobile phones and tablets, to be charged so they can be switched on for security staff were announced by US authorities on Sunday.

The heightened security comes amid reports two terror networks are working together on a bomb that could evade existing measures.

Last week the DfT said undisclosed extra measures at British airports were not expected to cause ''significant disruption'' to passengers and noted that the official UK threat status remained unchanged.

US officials were reported to have said the move to increase security at airports from where aircraft fly directly to the US was the result of intelligence that al Qaida's chief bomb maker, Ibrahim Hassan al-Asiri, who is thought to be based in Yemen, had linked up with jihadists in Syria to pass on his skills.

Last week Prime Minister David Cameron said decisions had been made based on "the evidence in front of us" and in co-operation with America.

''The safety of the travelling public must come first. We mustn't take any risks with that," he told the BBC.

''I hope this won't lead to unnecessary delays but it's very important that we always put safety first, and we do.''

Sir Malcolm Rifkind, the chairman of the Intelligence and Security Committee, said the increased airport security measures were "unavoidable".

Writing in the Sunday Telegraph, he said jihadi extremists were deploying "devilish technical skill" to create ever more sophisticated devices to evade existing security measures.

Have you been asked to charge your phone before boarding a flight? Let us know.