By Theo Leggett
Europe business reporter, BBC News
Airlines which advertise cheap fares and fail to mention extra charges will be acting illegally under new rules approved by the European Parliament.
The EU wants the pricing of air fares to become more transparent
All taxes, fees and surcharges must be included, so that prices can be easily compared, the draft regulation says.
The move is the latest attempt by the EU to present a consumer-friendly face to the world, following its crackdown on mobile telephone roaming charges.
It still has to be approved by national transport ministers.
Low-cost airlines, whose fares are sometimes lower than the taxes charged on their flights, are likely to be most affected.
In some cases consumers booking over the internet learn about the taxes only at the final stage of the process, just before making the purchase.
The European Commission, which proposed the measure last year, said it had received numerous complaints.
But Europe's largest budget carrier, Ryanair, has said it welcomes the move.
"Airline passengers must be treated like other consumers and thus have a right to clear and full information of the price they finally pay," said Lithuanian MEP Arunas Degutis, who piloted the regulation through the parliament.
The proposal is part of a much broader reform of EU aviation law, but parliament sources are optimistic that agreement with member states will be possible, and the law can get final approval in mid-2008.
MEPs say that consumers should also be told how much of the ticket price is being spent on airport or onboard security.