DUBAI: Emirates airline has changed pilot and flight attendant rosters on flights to the United States following the sudden US travel ban on seven Muslim-majority countries, highlighting the challenges facing airlines to deal with the new rules.

The world's largest long-haul carrier, which flies daily to 11 US cities, has made "the necessary adjustments to our crewing, to comply with the latest requirements," an Emirates spokeswoman told Reuters by email on Sunday. She added US

flights continue to operate to schedule.

President Donald Trump on Friday temporarily suspended the entry of people from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen. The decision caught airlines off guard, according to the International Air Transport Association.

"I cannot think of anything comparable. This brings a mix of administrative confusion, impact and uncertainty for many travellers as well as practical operational headaches and complexities for airlines in planning their flight programmes," independent aviation consultant John Strickland told Reuters.

The ban applies to pilots and flight attendants from the seven countries, even though all flight crew who are not US citizens already need a special visa to enter the country.

Nicoley Baublies, from the German cabin crew union UFO, said the move was very unusual and meant uncertainty for airlines in terms of planning.

"Lufthansa has always ensured it has very diverse crews, with staff of different nationalities and that means that we are for the first time in decades having to look at where people come from," he told Reuters at Frankfurt airport.

A spokesman for 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.

Another Emirates spokeswoman said 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.

Meanwhile, a spokesman for Etihad Airways of Abu Dhabi said the airline has "taken steps to ensure there will be no issues for flights departing over the coming weeks." But amid confusion over enforcing the ban, it is unclear if the ban applies to dual nationals - those who hold one passport from a country on the list and another from a non-US country that is not.

Etihad said on its website that dual citizens could travel to the U.S. using their non-banned passport. IATA have told its members that the ban does not apply to dual nationals if they have a passport not on the list, according to an email seen by Reuters.

However, the Guardian reported on Saturday, quoting State Department officials, that dual nationals were banned.

US officials said on Sunday holders of green cards need to check with a U.S. consulate and will be cleared on a case by case basis.