Etihad Airways pre-clearance at Abu Dhabi airport proves a bonus after Donald Trump's travel ban

A US border post in Abu Dhabi has handed local carrier Etihad Airways an advantage over its Persian Gulf rivals following President Donald Trump's moves to curb immigration from a clutch of mainly Muslim countries.

The so-called pre-clearance facility means that travellers from the affected nations who think they qualify for entry can have their paperwork processed before leaving the Middle East, rather than risk being turned away on arrival in the US, Etihad Chief Executive Officer James Hogan said Monday.

"In these times of uncertainty people are moving over to Abu Dhabi to take advantage of that clearance," Hogan said at a briefing in Serbia. "If you're going into secondary search that's better happening in Abu Dhabi than maybe on arrival in New York. So we're seeing an increase in bookings."

Gulf rival Emirates, the world's biggest long-haul airline, said last week that there had been a 35 percent drop in the rate of US bookings in the wake of Trump's initial ban on travel from seven nations -- later cut to six -- with demand recovering only slowly. Its Dubai hub has no pre-clearance option.

The US Customs and Border Protection facility at Abu Dhabi International Terminal 3, which opened in 2014, allows passengers to complete immigration and customs inspections before they depart. It's the only such outpost in the Middle East and one of a handful outside North America, though the federal government has said it could seek to add more as part of a push to combat terror threats before would-be perpetrators even board a plane.

Etihad currently serves New York, Washington, Chicago, Dallas, Los Angeles and San Francisco in the US, and says it doesn't plan to add further destinations.

The first version of Trump's travel ban, later overturned by the courts, forced Emirates to change pilot and flight attendant rosters on flights to the US as the crew may not have been allowed to enter the country.

Meanwhile, Australians have reported facing long delays and, on some occasions, have been detained while trying to enter the US in the wake of the travel ban.

Tourism economists in the US are already predicting a whopping 4.3 million fewer foreign visitors to the US this year, an estimated $US7.4 billion ($A9.7 billion)loss of revenue.