Air passengers flying to the United States will have to make sure their mobile phones and tablets are charged as part of increased precautions due to the threat of terrorist attacks.
The new restriction means that any electronic device that has a flat battery will not be allowed on to the flight, the Department for Transport (DfT) advised.
Yesterday, US authorities announced that airport security staff may ask travellers to turn on their electronic equipment to show they have power.
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.
Changes were announced after Washington Homeland Security Secretary Jeh Johnson ordered beefed up security at foreign airports from where aircraft fly directly to the US.
US officials were reported to have said the move 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.
Writing in yesterday's Sunday Telegraph, he said jihadi extremists were deploying "devilish technical skill" to create ever more sophisticated devices to evade existing security measures.
And he warned of the dangers of "complacency" among the public in the face of the failure of the terrorists to mount any successful mass casualty attack in the UK since the 7/7 bombings in London in 2005.