"No surrender": that was the defiant message from Ryanair, after the Treasury warned it would crack down on excessive charges for using credit and debit cards.

Europe's biggest budget airline applies an "administration fee" of £6 per passenger per flight, and says it will not change its policy. The carrier issued a terse statement, saying only: "Ryanair, the UK's favourite airline, confirms that it does not impose any debit or credit card fees."

At present, all airlines must offer at least one way to secure the advertised lowest fares. On Ryanair, the only way to dodge the administration fee is to pay with a special pre-paid cash passport. The airline's case for immunity from new laws appears to turn on a semantic argument that the availability of this means of "free" payment is unrelated to its obligations about advertised prices.

Even though Richard Lloyd, of the Consumers' Association, declared it was "game over for airlines," the UK carriers said they had no intention of making changes ahead of legislation. They have another year to continue extracting high charges from passengers before any new law takes effect.

Britain's leading low-cost carrier, easyJet, currently charges a minimum fee of £8 a booking, with additional charges for credit cards. Only holders of hard-to-obtain Visa Electron cards can avoid these fees. The airline's director of communications, Paul Moore, said "Until we see the detail of the proposals, we're not planning to make any changes. We've built our reputation and success on fairness and transparency."

Only Monarch, which makes no charge for debit cards and a flat £10 fee for credit-card payments, welcomed the change.