Australians are caught up in the travel chaos sparked by the conflict in the Middle East, as flights are cancelled and diverted.

Doha Airport reopened its air space on Tuesday morning, after dozens of flights heading to the Middle East were diverted or cancelled after Iran attacked a US air base in Qatar overnight.

But the chaos continued, even after US President Donald Trump’s announcement of a ceasefire. Flights from dozens of airlines, including Qatar Airways, Emirates, Etihad and FlyDubai, were diverted.

Qantas confirmed that flight QF33 from Perth to Paris had been turned back.

Flight QF9 from Perth to London was diverted to Singapore. Its passengers and crews would be given overnight accommodation until they can be rebooked.

“Due to airspace closures and congestion through the Middle East resulting in air traffic restrictions, QF9 (Perth-London) has been diverted to Singapore and QF33 (Perth-Paris) is returning to Perth,” a Qantas spokesperson said.

“We continue to monitor airspace availability closely and will alter our schedule as required. We thank our customers for their patience and understanding.”

Two Virgin flights operated by Qatar and three Qatar Airways flights from Melbourne, Sydney, Brisbane, Adelaide and Perth were also diverted.

A Virgin Australia spokesperson said the airline’s scheduled services to Doha, operated by Qatar Airways, were expected to operate later on Tuesday with delays.

“We are working closely with our partner, Qatar Airways, to support passengers that have been impacted,” they said.

Travellers heading to Australia’s international airports on Tuesday were warned to check with their airlines for any disruptions.

The usually busy airspace stretching from Iran and Iraq to the Mediterranean has been largely empty of commercial air traffic for 10 days since Israel began strikes on Iran on June 13, as airlines divert, cancel and delay flights through the region due to airspace closures and safety concerns.

Leading Asian carrier Singapore Airlines, which described the situation as “fluid” cancelled its Sunday flight from Singapore to Dubai but had been scheduled to resume on Monday.

Similarly, Flightradar24 departure boards showed British Airways  planned to resume Dubai and Doha flights on Monday after cancelling routes to and from those airports on Sunday.

Air France KLM cancelled flights to and from Dubai and Riyadh on Sunday and Monday.

Qatar Airlines said on Tuesday that the airspace was open, significant delays are expected.

“As operations resume, we anticipate significant delays to our flight schedule. We would advise passengers to check qatarairways.com or the Qatar Airways mobile application ahead of travel,” it said.

With Russian and Ukrainian airspace also closed to most airlines due to years of war, the Middle East had become a more important route for flights from Europe to Asia and Australia. Amid missile and air strikes during the past 10 days, airlines have routed north via the Caspian Sea or south via Egypt and Saudi Arabia.

Added to increased fuel and crew costs from these long detours and cancellations, carriers also face a potential hike in jet fuel costs as oil prices rise following the US attacks.

Safe Airspace, a website run by OPSGROUP, which shares flight risk information, noted on Sunday that US attacks on Iran’s nuclear sites could heighten the threat to American operators in the region.

In the days before the US strikes, American Airlines suspended flights to Qatar, and United Airlines and Air Canada did the same with flights to Dubai. They have yet to resume.

-with AAP