BRUSSELS - One in three European airline and travel websites conceals the true cost of flights until consumers are close to booking, according to a report from the European Commission, which yesterday threatened new measures against the industry if the abuses continue.

The warning from the commission follows a survey which found that dozens of well-known travel operators, budget airlines and national carriers are probably in breach of European Union consumer protection law.

Data from 13 of the 16 countries that took part in the survey last September show that, of 386 websites checked, 137 had problems serious enough to warrant investigation. Only half of these sites have so far rectified the problems.

Some operators advertise flights at a token price but at a late stage of the booking, add airport taxes, booking or credit card fees, or other surcharges.

The survey, coordinated by the European commissioner for consumer protection, Meglena Kuneva, found that many websites present more than one type of irregularity.

The biggest reported problem was misleading pricing, affecting 79 websites under investigation, while 67 sites gave consumers contract details in the wrong language or had optional services added on automatically unless a box was unchecked.

When she released the findings yesterday, Ms Kuneva promised to intervene if there is no improvement by May 2009, according to an official briefed on the issue who requested anonymity because he was not authorised to discuss the report prior to publication.

Norway, one of the few countries to make the results of its national survey public, found that Austrian Airlines added a booking fee of 100 kroner (S$26.80) per ticket, which was not included in the advertised price. The airline has since changed that policy.

Ryanair, the budget carrier based in Ireland, included a 'priority boarding' fee of 50 kroner as a preselected option and Blue 1 of Finland added a charge for cancellation insurance to every booking automatically.

In an e-mailed statement, a spokesman for Ryanair denied the claims made against the airline.

In all, about 80 companies appear to have broken consumer protection rules. Of the 48 websites checked by the Belgian authorities, 30 had irregularities, and 13 of them have since resolved the problems.

The European Commission said that it is prevented from identifying all the airlines concerned by the policies of the national enforcement authorities that provided the data for the survey.

But Monique Goyens, director-general of BEUC, a European consumer organisation, appealed for more information.

'We would like to have the names, and if there is no progress in the coming months, we are going to undertake our own study and name and shame,' she said.

'You have very good consumer protection legislation but it is not enforced,' she added.