Airports have said jet fuel could run short within three weeks in Europe if oil supplies do not start to flow through the strait of Hormuz, raising concerns over flight cancellations in the UK and EU going into the summer holiday season.

Jet fuel shortages will become so acute without the resumption of supplies from the Middle East that cancellations across Europe will be inevitable, disrupting travel plans for potentially millions of passengers.

The warning came from Airports Council International (ACI) Europe, which wrote to the EU’s energy and transport commissioners saying the bloc is three weeks away from shortages.

The warning will raise concerns of a risk of rolling flight or holiday cancellations if the US and Israel’s war on Iran continues. Oil prices have soared since the start of March after Iran effectively closed the strait of Hormuz, a key shipping route for exports from the Gulf, in retaliation.

Donald Trump this week announced a two-week ceasefire, but Brent crude oil prices remained at about $96 a barrel on Friday amid concerns over whether it would hold. Before the war, oil traded at about $72.

“If the passage through the strait of Hormuz does not resume in any significant and stable way within the next three weeks, systemic jet fuel shortage is set to become a reality for the EU,” the letter said.

Jet fuel prices have soared since the end of February after the attacks on Iran ordered by Trump and Benjamin Netanyahu, the Israeli prime minister. Global jet fuel prices at the end of last week had more than doubled compared with last year to $1,650 a tonne, according to figures tracked by Iata, an airline lobby group.

The worst hit region has been Asia, with prices up 163% year on year. However, prices in Europe were still up by 138%, amid a global scramble to secure fuel.

Rico Luman, a senior economist covering transport at ING, an investment bank, said that some airlines might be forced to cancel flights within weeks as fuel reserves run down, particularly at smaller airports further from big hubs.

“Smaller airports really rely on deliveries and the stocks they have on site,” said Luman, with typical reserves only covering four to five weeks.

He added that airlines would be likely to cut flights on less popular leisure routes first because there would be fewer passengers to rebook. He said: “That could be the next couple of weeks if shortages loom.”

Smaller airlines in the UK have already been forced to cancel some flights. Skybus closed its Newquay to London Gatwick route last week, while Guernsey-based Aurigny cut journeys between the Channel Islands and London City, Paris and south-west England.

Air New Zealand, AirAsia X, Vietnam Airlines and the Scandinavian airline SAS are also among the global airlines that have already cut flights in response to higher prices.

A UK government spokesperson said British aircraft have not reported any disruption to fuel supplies and are operating as normal. “We are engaging with British carriers to support their operations against the backdrop of war in the Middle East, and to limit the impact on passengers,” the spokesperson added.

Michael O’Leary, the chief executive of Ryanair, this week said that the airline, Europe’s largest, is considering cutting 10% of its flights.

The last cargo of European jet fuel to pass through the strait of Hormuz before the war began is due to arrive in Copenhagen on Saturday, after the same tanker delivered a part cargo to Rotterdam on Monday, according to the shipping data provider Vortexa.

The final tanker of Gulf jet fuel destined for the UK arrived in Kent on the Maetiga vessel from Saudi Arabia on Tuesday.

Europe has typically sourced more than 60% of its jet fuel from Gulf refineries, of which more than 40% was shipped through the strait of Hormuz. Iran’s chokehold on the vital trade strait has forced European buyers to compete with Asia for fresh cargoes from other parts of the world as the last Gulf deliveries have trickled in.

The global market for jet fuel has been particularly exposed to the Gulf disruption because there are fewer alternative routes for exports, according to the Australian investment bank Macquarie. While some crude exports have been able to bypass the strait via pipelines, jet fuel does not have these options available.

The fare rises will feed through into higher inflation, but outright shortages of jet fuel could cause greater economic damage if they force people and businesses to abandon travel or hold off on exports.

ACI warned of “increasing concerns of the airport industry over the availability of jet fuel as well as the need for proactive EU monitoring and action”, with supplies further being hit by “the impact of military activity on demand”.

The problems could become particularly acute at the start of the peak summer season “when air travel enables the whole tourism ecosystem upon which many economies rely”, ACI said in the letter, first reported by the Financial Times.

Willie Walsh, the Iata director general, said that even if the strait of Hormuz were to remain open, “it will still take a period of months to get back to where supply needs to be, given the disruption to the refining capacity in the Middle East”.

Before the crisis, Iata had predicted 4.9% year-on-year growth in passenger traffic for 2026.