The world's largest long-haul carrier, Emirates, announced on Monday that it had made "necessary adjustments" to its crewing in order to comply with the latest US requirements, adding that Emirates' 11 daily flights to the US would continue to operate to schedule.

US President Donald Trump on Friday suspended the entry of people from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen. The ban also applies to pilots and flight attendants from the seven countries.

An Emirates spokeswoman told the news agency Reuters that the impact of the ban on operations would be minimal. The airline employs over 23,000 flight attendants and about 4,000 pilots from around the world, including the United States, Europe and the Middle East.

The decision has caught airlines largely off guard. Independent aviation consultant, John Strickland, told Reuters that he couldn't think of "anything comparable."

"This brings a mix of administrative confusion, impact and uncertainty for many travelers as well as practical operational headaches and complexities for airlines in planning their flight programs," he said.

Nicoley Baublies, from the German cabin crew union UFO, said the move was very unusual and meant uncertainty for airlines in terms of planning. "Trump reacts in 140 characters, we don't know what it means - for people with the wrong entries in their passports or with dual nationality or married to someone from one of the countries affected, are they allowed to travel?" he told Reuters.

Challenge to business

German flagship carrier Lufthansa said on Sunday it was too early to comment on the effects of the order but that airlines and passengers were required to follow the new rules.

Etihad Airways of Abu Dhabi said it had taken steps to "ensure there will be no issues for flights departing over the coming weeks," while Japan Airlines (JAL) announced it had begun "screening passengers from the countries affected before their departure for the United States."

However, it's still unclear if the ban applies to dual nationals - those who hold one passport from a country on the list and another from a non-U.S. country that is not.

International aviation agency IATA has told its members that the ban does not apply to dual nationals if they have a passport not on the list. But the British newspaper the Guardian reported on Saturday that dual nationals were banned, quoting officials from the US State Department.

Meanwhile, a "handful of people" were stopped from flying to the United States from Dubai International Airport following the US travel ban, the airport operator's chief executive said on Monday. 

"We don't have the exact figures but literally a handful of people have had to be looked after and repatriated to their point of origin," Dubai Airports Chief Executive Paul Griffiths told the Dubai Eye radio station in an interview.

Dubai airport is the world's busiest for international travel and the hub for Gulf airline Emirates. There are concerns the restrictions could dampen travel demand.

"Ultimately this could feed through to the role airlines play in the global economy in supporting business and tourism due to as yet unquantifiable impacts on demand and cost," independent consultant John Strickland said.

And Cockpit union's Nicoley Baublies noted that airlines were usually among the first affected by global crises. "We hope it doesn't mean that seats are left empty because people don't know where they can travel with which passport," he told Reuters.

uhe/jd (Reuters, AFP, dpa)