Ryanair’s profits have fallen sharply as the war in the Middle East sent jet fuel prices soaring and customers became reluctant to book flights.

The Irish airline’s pre-tax profits fell 34% to €593m (£503m) between April and June, while sales remained stable as the company was forced to cut fares to stimulate demand.

Ryanair also said it expects summer fares to be slightly lower than last year due to “consumer hesitancy” around air travel.

The price of fuel for an aircraft has soared since the US and Israel launched attacks on Iran in February and, although Ryanair said it had “covered” or reached agreements for most future fuel costs, those not included in these agreements had more than doubled.

Crude oil prices hit $90 a barrel for the first time in a month on Monday, before retreating slightly, after a weekend of intense exchanges of fire between the United States and Iran.

Traffic through the Strait of Hormuz, an essential route for global oil and gas supplies, has been halted.

An interim peace deal last month brought some respite to oil and energy prices, but they soared again when negotiations collapsed and fighting resumed.

The airline warned that its results for the year will be “very sensitive” to external factors such as the escalation of conflicts in the Middle East and Ukraine, as well as the price of unhedged jet fuel.

Fares for the key summer period between July and September are on track to be “modestly” lower than last year, with many passengers booking closer to departure than normal.

The company’s chief financial officer, Neil Sorahan, said flights on its popular Mediterranean routes were still full. “People [are] “I want to get away as much as ever, even though we booked a little later,” he said.

Between April and June, Ryanair’s revenue increased by 1% to €4.4 billion.

While the number of passengers increased by 6% to 6.1 million, helped by the Easter holiday in April, fares fell 6% as the airline cut fares to attract travelers concerned about the Iran war.

Ryanair’s share price fell 5% on Monday.

Russ Mould, investment director at AJ Bell, said Ryanair was in a better position than many of its rivals, but nevertheless “visibility is worse than San Francisco airport when the fog comes in.”

“The renewed escalation of hostilities in the Middle East is futile and without a lasting resolution, it appears difficult times will continue for airlines and the travel space.”