WASHINGTON (BLOOMBERG) - Airline and travel-industry groups are quietly expressing concern about a plan under consideration by United States security authorities to prohibit passengers from carrying their laptop computers into the cabin on flights from Europe.

Extending electronics restrictions - now in place for travel from some Middle Eastern and African airports - to Europe would disrupt one of the world's busiest and most lucrative travel markets just ahead of the peak summer tourism season.

It could also hinder business passengers' ability to work on their laptops on long-haul routes across the Atlantic.

Two travel trade groups, the Global Business Travel Association (GBTA) and the US Travel Association, issued statements Thursday saying genuine security risks should be addressed, but also urging the US Homeland Security department to be as flexible as possible to minimise disruptions.

"The question remains whether the targeted application of policies banning personal electronics is an effective measure to reduce the risk of terrorism," Michael McCormick, GBTA executive director, said in a statement on Thursday.

More than 3,000 flights are expected to arrive in the US from the European Union each week this summer. The US is the world's second-largest market for spending on business travel, following China, according to the GBTA. Global spending for business travel topped US$1.3 trillion (S$1.8 trillion) and is projected to reach US$1.6 trillion by 2020, the group said.

Homeland Security Secretary John Kelly met in Washington on Thursday with US airline officials to discuss details of a possible expansion. The meeting was to include representatives of American Airlines, Delta Air Lines and United Airlines, as well as industry trade group Airlines for America, according to three people familiar with the ongoing discussions. Agency spokeswoman Jenny Burke said there would be no announcement on Thursday.

The US announced on March 21 that electronic devices larger than smartphones would be banned from cabins on flights originating from eight countries, impacting global hubs including Dubai, Abu Dhabi and Istanbul.

The action, which affects major carriers such as Emirates, Qatar Airways and Turkish Airlines, resulted from fears that bombs capable of downing an airliner could be hidden in the devices.

The Department of Homeland Security (DHS) is considering an expansion of that order, but no decisions have been made, Burke said in an email. "DHS continues to evaluate the threat environment and will make changes when necessary to keep air travellers safe," she said.

Airline representatives have also expressed their concern to Congress, according to two congressional staffers who asked not to be named because they are not authorised to discuss the discussions.

US airlines have been pushing alternative solutions they believe will address security concerns while sidestepping measures that would block business travellers from working on laptops and prevent other fliers from viewing movies or reading books on tablets, according to the staffers and an industry official. The official asked not to be named because he was not authorised to speak about discussions with the government.

Airlines have suggested measures such as asking passengers to turn on their electronic devices and subjecting all devices to explosive-detection swabs. Another strategy might be to use CT x-ray technology, which uses scores of x-ray images from multiple vantage points to provide a higher definition image, the person said. CT is used for checked bags but isn't available at checkpoints for carry-on luggage.

At the same time, the airlines will do whatever is necessary to address any legitimate security threat, the industry official said.

Finding a way to expand trusted-traveller programs, such as the Transportation Security Administration PreCheck, may also be a solution, McCormick of the GBTA said.

Passengers who agree to be screened for terrorist ties now get expedited screening at US airports, but the program is not recognised by airport security workers in other countries.

TERRORIST GROUPS

DHS Secretary Kelly and Representative John Katko, a New York Republican who is chairman of the House Transportation Security Subcommittee, have said in recent weeks that the initial measures were prompted by intelligence that terrorist groups have gotten better at concealing explosives in electronic devices.

A bomb installed in a laptop or tablet may not be detectable by existing x-ray machines at security checkpoints.

The current laptop ban on flights from eight countries in the Middle East and Africa doesn't apply to travel that originates in the US to those countries.

Some carriers serving those routes have begun loaning equipment to premium customers. Business-class travelers on Qatar Airways hand over their laptops at the gate for storage in the hold and receive specially purchased computers. Etihad Airways PJSC planned to provide Apple iPads, according to a March announcement.

MAKING PREPARATIONS

Meanwhile, US and European airlines are preparing for an anticipated widening of the ban.

Air France-KLM Group and Deutsche Lufthansa AG say they're making preparations for the moratorium on devices on flights from Europe, including tablets and games consoles. The European Commission has written to President Donald Trump's administration to urge cooperation on any new measures.

"We are in contact with our partners and the authorities, and we're preparing for the possibility," Air France spokeswoman Ulli Gendrot said by phone.

Lufthansa has been working internally on different scenarios for responding to any extension of the ban, spokesman Helmut Tolksdorf said. Both companies have close ties to major US operators, with Air France-KLM allied to Delta Air Lines and Lufthansa partnered with United Continental Holdings.

US airlines also have been discussing a potential expansion of the ban with officials at DHS and TSA for several weeks, according to one of the US people briefed on the talks.

LOAD FACTORS

While a broadening of the restrictions could "only be a negative" for airlines, making on-time departure more challenging and adding costs for loaner devices, it might at least amount to a "zero-sum game" if applied universally to trans-Atlantic operators, said Mark Simpson, an analyst at Goodbody Stockbrokers in Dublin.

Carriers impacted by the existing ban have reported a slide in US load factors as some travellers take alternative routes, though that will become less of an option in the event of expanded curbs.

Airports Council International, which represents hubs around the world, said it has been discussing the issue with bodies including the International Air Transport Association, the International Civil Aviation Organisation, the European Commission and TSA in anticipation of the ban being extended.

"We're trying to make sure that there is good coordination involving airports and airlines," said Robert O'Meara, a spokesman for ACI Europe. "The key thing is to make sure the message is communicated in a coherent way."

Shortly after the original ban was announced the Flight Safety Foundation, an aviation safety group, warned that it could create risks by shifting more lithium-battery powered devices to cargo holds. Lithium-powered batteries have been linked to fires.

Officials are coordinating with the Federal Aviation Administration to provide carriers with a bulletin on the proper handling of batteries, DHS spokeswoman Jenny Burke said last month.