Iran's flights to Gulf hubs halted as US deadline hits

Iranian flights to Gulf neighbours including travel hub Dubai appeared to have been cancelled on Thursday after a US deadline passed for global firms to halt work with Iran's airlines, a major step in a campaign President Donald Trump calls "economic D-Day".

With the US-Israeli war against Iran largely stalemated for months on the battlefield, Washington has announced a shift in tactics to extend the reach of its financial sanctions by targeting companies from third countries that do business with Iranian firms, a practice known as "secondary sanctions".

Trump referred to the new strategy last month as "economic D-Day", comparing it to the assault on Nazi-controlled France in World War Two by the United States and its allies.

The US Treasury had set September 23 as the deadline for companies worldwide to comply with an order to stop doing business with Iranian airlines. Washington says the aim is to ground the entire global Iranian civilian fleet.

Iran threatened on Wednesday to retaliate against any neighbouring countries that comply with the US ban on its flights, by making their airports "unusable".

There were no immediate public announcements from countries that they were halting flights, but Iran's ISNA news agency said all flights to the United Arab Emirates, the Gulf's biggest travel hub, had been halted as of midnight.

No arrivals or departures to Iran were visible on the website of Dubai or Abu Dhabi airports on Thursday. Websites of at least two Iranian airlines, Qeshm and Varesh, showed UAE flights had been cancelled. The UAE's General Civil Aviation Authority and Dubai Civil Aviation Authority did not respond to requests for comment.

The website of Iran's Imam Khomeini Airport in Tehran showed departures and arrivals on Thursday were still scheduled to and from countries including Afghanistan, Armenia, China, Iraq, Pakistan, Tajikistan and Turkey, but not nearby Gulf states. ISNA said a flight to Tajikistan had also been turned back because Turkmenistan had closed its airspace.

A flight ban, if sustained, could deepen Iran's isolation and worsen an economic crisis in the country, which is already facing a US blockade of its ports at sea.