The no-frills carrier said it made profit after tax of €15m (£12.8m) over the final three months of 2023, its third quarter, compared to the €211m it achieved in the same period a year previously.

'Huge change' to UK's food supply from tomorrow - and prices could rise | Money blogA poll of analysts had expected a figure of €49m.

The sum came in lower despite a 7% rise in passenger numbers and fares being 13% higher.

Europe's largest airline by passenger numbers blamed the decision by some booking sites, including booking.com and Kayak, to remove it from their listings in early December.

The airline's boss Michael O'Leary had warned earlier this year that the move, by firms he described as "pirates", had harmed third quarter profitability as it had forced Ryanair to cut fares to fill seats.

Another factor behind the slump in profits was a 35% increase in fuel bills.

Ryanair said it now expected an after-tax profit of between €1.85bn and €1.95bn for the 12 months to the end of March.

That is lower than its previous forecast of just over €2bn at the top of the range.

Shares fell by 3% on the update.

"While traffic and fares were ahead of prior year, close-in Christmas/New Year loads and yields were softer than previously expected as Ryanair lowered prices in response to the sudden (but welcome) removal of flights from OTA (online travel agent) pirate websites in early Dec," Ryanair said in a statement.

Ryanair, which had accused some firms of imposing additional charges on its customers and had initiated legal proceedings, said the impact would be temporary.

Chief financial officer Neil Sorahan told Reuters news agency on Monday it was already beginning to "fizzle out".

Mr O'Leary told investors one risk remaining to Ryanair's growth prospects was the possibility of further delays in the delivery of new, more fuel efficient, Boeing 787 MAX 8 aircraft.

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It expects to have seven fewer than anticipated in time for the summer peak and hopes MAX 10s will be with Ryanair during 2025.

Boeing was, last week, placed under manufacturing restrictions by US air regulators investigating the Alaska Airlines replacement door panel blowout of 5 January.

The measures prevent Boeing from increasing production rates.

"We continue to work closely with Boeing to minimise delivery delays and improve quality control in both Wichita and Seattle", he said.

"While the recent MAX 9 grounding was a disappointing setback, we don't expect it to affect the MAX 8 fleet or the MAX 10 certification."