RYANAIR is introducing a new 2pc credit card fee on bookings from tomorrow.
The airline said it would impose the new charge as well as its €6 administration fee, meaning Irish customers would be paying booking charges on the double.
However, the administration fee will be scrapped in Ireland in two months' time and built in to higher flight fares instead.
Ryanair said it was making these changes under pressure from the Office of Fair Trading in the UK, which is making it illegal to add surprise debit card charges at the end of the booking process.
Currently passengers can avoid the €6 administration charge if they pay by Ryanair Cash Passport, but the OFT has ruled that airlines cannot impose extra charges for other debit cards which should be treated like cash payments.
However, it is allowing extra credit card charges as long as they are clearly signalled.
Airline spokesman Stephen McNamara said he understood that customers would be unhappy about the changes, but that the separate new credit card charge was an "unhappy consequence" of the OFT's decision that they couldn't charge added fees to customers paying by any type of debit card.
"Our preference would have been never to have had this enforced," he said.
The airline said that the €6 administration fee would continue in place here until February 1, after which it would be scrapped and the €6 would be absorbed into higher flight fares.
However, the 2pc credit card charge will be a permanent fixture, and the only way to avoid it will be to pay by debit card, including but not limited to the Ryanair Cash Passport.
The 2pc charge will be levied on top of the final flight price, including any extra charges such as baggage or priority boarding.
Mr McNamara said that the lowest flight prices in the UK, where the new charging regime was being rolled out this week, had already been adjusted from £12 (€14.86) to £18 (€22.29) to build in the administration fee to the advertised price.
This will also happen in Ireland in February, which will mean, for example, that the lowest fare will rise from €16 currently to €22.
The new charging regime would have been introduced at the same time across Europe, but is being phased in at different times in Ireland, Germany and Spain to allow contracts run out with Mastercard, which operates the Ryanair Cash Passport system.
Mr McNamara said that though this was messy, it reflected the fact that contracts were in place.