Singapore Airlines (SIA) and budget carrier Scoot said yesterday that they were diverting all flight routes from Iranian airspace.
"In view of the latest developments between the US and Iran, all SIA flights in and out of Europe are diverted from Iranian airspace," SIA said, adding that the carrier has not operated flights over Iraqi airspace since 2012.
The affected flights have been taking different flight paths since Monday, and the new routes do not significantly change flight times, it said.
"We are closely monitoring the situation in the region and will take the appropriate precautions if necessary," SIA told The Straits Times.
Scoot, which is a subsidiary of SIA, said that all its flights in and out of Europe and Saudi Arabia will not be flying over Iranian airspace.
Tensions in the region increased yesterday after Iran fired ballistic missiles at Iraqi bases housing United States-led troops.
Shortly after the attacks, the US Federal Aviation Administration (FAA) said it was banning US-registered carriers from flying over Iraq, Iran, the Gulf of Oman and the waters between Iran and Saudi Arabia.
It cited "heightened military activities and increased political tensions in the Middle East".
Non-US airlines are not directly affected by the FAA ban, but foreign carriers and their national regulators typically consider US advice carefully when deciding where to fly.
Dubai-based Emirates and Flydubai each cancelled a return flight to Baghdad yesterday.
Qantas Airways said that it was adjusting flight paths to avoid airspace over Iraq and Iran until further notice, adding up to 50 minutes to Perth-London flights and requiring it to reduce passenger numbers to carry the necessary fuel.
Malaysia Airlines said its planes did not fly over Iraqi airspace and added that it would reroute flights to avoid Iran.
With some commercial carriers still serving the region and others flying over the airspace, the International Air Transport Association (Iata) has issued a statement reminding countries of their obligation to communicate potential risks to civil aviation.
A coordination team operated by Iata and the International Civil Aviation Organisation has been activated as a standard precautionary measure, in the event that contingency measures are required by airlines, Iata said.