The International Air Transport Association (IATA) warned on Friday that Europe could see flight cancellations by the end of May because of jet fuel shortages, as supply disruptions linked to the Middle East conflict continue to strain global markets.

“The International Energy Agency‘s (IEA) assessment of potential jet fuel shortages is sobering,” IATA Director General Willie Walsh said in a statement.

Walsh said the industry group had also estimated that “by the end of May, we could start to see some cancellations in Europe for lack of jet fuel,” adding that such disruptions are already taking place in parts of Asia.

He said airlines are working to secure alternative supply routes, but stressed that governments must also prepare contingency plans in case fuel rationing becomes necessary.

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“Along with doing everything possible to secure alternative supply lines, it’s important that authorities have well-communicated and well-coordinated plans in place in case rationing becomes necessary, including for slot relief,” Walsh said.

The warning followed the IEA’s assessment that European countries could face a jet fuel shortage within the next six weeks as supplies from the Middle East decline because of the Iran war.

The IEA told Anadolu on Thursday that the outlook would depend on whether European countries can replace lost Middle Eastern supply with imports from other international markets. It said the Middle East accounts for 75% of Europe’s net jet fuel imports.

Energy prices have surged and shortages have emerged in several fuel types as the Iran war, which started on February 28, triggered the closure of the Strait of Hormuz and attacks on energy facilities.

Rising fuel costs and supply strains have already caused flight disruptions and cancellations, while governments in Asia and Europe have sought to limit the fallout.