Iraq's Najaf airport has closed to Iranian flights, the head of Tehran's Imam Khomeini Airport City said to state news on September 25.

Najaf had been Iran's remaining air link to Iraq in recent days. Baghdad and Muscat stopped accepting Iranian flights ahead of US secondary sanctions on services to Iranian carriers, which took effect on September 23, after US Treasury Secretary Scott Bessent warned that foreign firms fuelling, handling, or selling tickets for Iranian airlines will be cut off from the dollar system.

The closure also shuts the main air route for Iranian pilgrims to the Shia shrine cities of Najaf and Karbala, leaving Iranian travellers more dependent on overland routes and third-country hubs.

"From 2 am today, it was announced that Najaf airport is closed to Iranian flights," Ramin Kashef Azar, managing director of Imam Khomeini Airport City, said. He said the director of Najaf airport had informed Iran's Civil Aviation Organisation (CAO) by phone.

Flights to Najaf by Iran Air, Fly Persia, Taban Air and Saha Airlines were cancelled from the early hours, Kashef Azar said. A Meraj Airlines flight to Najaf left Tehran at 8:30 am. Najaf airport later prevented passengers from boarding a Meraj flight to Mashhad, and the aircraft returned empty, Lebanese outlet This Is Beirut reported.

The CAO is in talks to bring home Iranians who have travelled to Iraq and to return Iraqi nationals wishing to leave Iran, Kashef Azar said.

The airport's online flight board, last updated at 10:45 local time, listed 38 international departures and arrivals for the rest of the day. Nine were cancelled, all of them on Iraqi routes. The only other disruption was delays to three flights.

Eight of the cancelled flights were Najaf services run from Imam Khomeini's Salam Terminal, which handles pilgrimage traffic. The cancelled departures were Taban Air, Saha Airlines and Naseem Air flights.

The cancelled arrivals were from Iran Air, Fly Kish, Taban, Saha and Naseem. A Mahan Air arrival from Sulaymaniyah in Iraq's Kurdistan Region was also cancelled. One Meraj arrival from Najaf, due at 11:45 pm, remained on the board with no status, according to partner travel intelligence agency Emerging Travel on September 25.

Istanbul now carries most of the airport's international traffic. It accounted for six of the 16 departures and 10 of the 22 arrivals. Nine Iranian carriers serve the route, including Iran Air, Meraj, ATA Airlines, Iran Airtour, Varesh Airlines, Sepehran Airlines and Qeshm Air. Mahan Air, which suspended its Turkey flights in mid-September, was absent from the Istanbul schedule. Its flights to Beijing, Shanghai and Guangzhou were due to depart on time, as were services to Moscow and St Petersburg.

Caspian Airlines was flying to Ankara and Yerevan, and bringing in a flight from Denizli Cardak in Turkey, ET reported. Fly Kish also served Yerevan, and Meraj had a departure to Hanoi.

Kashef Azar said flights to China, Armenia, Russia, Southeast Asia and Turkey were continuing unchanged, apart from those of Mahan Air. Imam Khomeini International Airport, about 30 km southwest of Tehran, is Iran's main international gateway. Imam Khomeini Airport City, a state company, runs it and also manages the free zone around the airport.