Several Asian airlines said on Wednesday they were re-routing or cancelling flights to and from Europe because of fighting between India and Pakistan.

India attacked Pakistan and Pakistani Kashmir and Pakistan said it had shot down five Indian fighter jets in the worst fighting in more than two decades between the nuclear-armed enemies.

More than two dozen international flights were diverted to avoid Pakistan airspace. By Wednesday morning local time, airlines had cancelled 52 flights to or from Pakistan, according to FlightRadar24.

There were 57 international flights operating in Pakistan’s airspace when India struck, according to a Pakistan army spokesperson.

Domestic flights in both countries were also disrupted. India shut several airports and as a result, flights belonging to Air India, IndiGo, SpiceJet and Akasa Air were cancelled. IndiGo shares were down 1.8%.

Images from the flight tracking website showed that the northwestern airspace of India and Pakistan’s entire airspace were nearly free of civilian aircraft, barring a few flights.

The changing airline schedules are set to further complicate operations in the Middle East and South Asia regions for carriers, who are already grappling with a fallout from conflicts in the two regions.

A spokesperson for Dutch airline KLM said it was not flying over Pakistan until further notice. Singapore Airlines (SIAL.SI), opens new tab said it had stopped flying over Pakistani airspace since May 6.

Taiwan’s EVA Air (2618.TW), opens new tab said that it will adjust its flights to and from Europe to avoid airspace affected by the fighting between India and Pakistan for safety reasons. Shares were down about 1.7%. One flight from Vienna will be diverted back to that city, while a flight from Taipei to Milan will be diverted to Vienna for refuelling before continuing on to its destination, the airline said in a statement to Reuters.

Korean Air (003490.KS), opens new tab said it had begun rerouting its Seoul Incheon–Dubai flights on Wednesday, opting for a southern route that passes over Myanmar, Bangladesh, and India, instead of the previous path through Pakistani airspace.

Thai Airways (THAI.BK), opens new tab said that flights to destinations in Europe and South Asia would be rerouted starting early on Wednesday morning, while Vietnam Airlines (HVN.HM), opens new tab said tensions between India and Pakistan had affected its flight plans.

Taiwan’s China Airlines (2610.TW), opens new tab said that flights to and from destinations including London, Frankfurt and Rome had been disrupted, with some cancelled and others having to make technical stops in Bangkok and Prague to refuel and change crews, before taking longer flight paths. Its shares were down more than 2%.

Some flights from India to Europe were also seen taking longer routes. Lufthansa flight LH761 from Delhi to Frankfurt turned right towards the Arabian Sea near the western Indian city of Surat, taking a longer path compared to Tuesday, according to FlightRadar24.

Before Russia’s invasion of Ukraine many Europe-bound flights from Taiwan overflew Russia, but Taiwanese airlines are now banned after Taipei joined in Western sanctions on Moscow and generally fly over India, Pakistan and Central Asia.

The Association Of Asia Pacific Airlines voiced concern over the impact of conflicts on airline operations.

“Apart from cost and operational disruption, there are safety concerns as GPS spoofing interfering with flight operations over conflict zones is one of highest risks the industry faces,” it said in a statement.

GPS spoofing is a malicious technique that manipulates Global Positioning System (GPS) data, which can send commercial airliners off course.