Holidaymakers could be forced to ditch electronic devices or pay to have them posted on separately under anti-terror ­measures at airports.

Passengers travelling on selected UK flights will no longer be allowed to board with devices such as laptops, tablets and mobile phones unless they can demonstrate to security staff that they switch on. Devices that are flat and cannot be charged will be confiscated.

The guidelines initially applied to only US flights from Manchester and Heathrow, but the Department for Transport (Dft) has extended them to ­additional destinations and UK airports. It will not disclose which routes and airports are affected but the arrangements are thought to predominantly affect services to the US.

The move comes amid heightened anxiety over a possible terror plot to blow up jets, with UK airport security checks first ramped up on July 2 amid reports Islamist terrorists were planning to board planes with undetectable "stealth bombs" implanted in their bodies.

It emerged at the weekend that the checks would affect electronic equipment in passengers' hand luggage to prevent would-be bombers carrying dummy devices on to planes that were actually loaded with explosives.

However, airlines have ­conflicting policies over ­confiscated electronic devices. While British Airways and Virgin Atlantic confirmed yesterday that they would foot the bill to return devices to passengers, neither carrier operates transatlantic services direct from Scotland.

Only US Airways, United Airlines, Jet2 and Thomas Cook operate direct flights between Scotland and the US.

A spokeswoman for budget carrier Jet2, which flies from ­Glasgow to New York, said the airline was not commenting on its policy "at this stage".

However, Scots holidaymakers flying with US Airways to Philadelphia from either Glasgow or Edinburgh airports, or on its popular Glasgow-to-Florida route, will be expected to meet the cost of mailing devices on themselves.

In a statement, American Airlines Group - the parent company for US Airways and American Airlines - said: "Customers departing from certain European airports with electronic device that won't power on will be given the option to mail the device to their home or other location, discard the device, or be rebooked on a later flight at no charge."

A spokeswoman for AAG confirmed passengers choosing to mail a device separately would be "directed to the nearest shipping location to mail it themselves".

United Airlines also operates two flights from Edinburgh, to Chicago and New York, and a Glasgow to New York route. It has yet to disclose its policy.

A spokeswoman for Thomas Cook, which operates a Glasgow-to-Las Vegas service, said managers at the package holiday firm were holding talks yesterday to draw up its policy, but in the meantime advised passengers to charge devices in advance.

She said: "If you are unable to demonstrate that your phone or other electronic device can be switched on, you risk having to leave the device at the airport, which may also result in you ­missing your flight.

"Many airports now have ­charging facilities at the airport but demand for these will be intense, particularly at this time of the year.

"Customers are also advised to switch on their electronic devices before they reach the security check areas, to cut down on ­potential delays."

A DfT statement said: "For ­obvious reason we will not be commenting in detail on the routes affected. We will work with the aviation industry to minimise disruption as far as possible."