EasyJet is tearing up the rulebook for budget airlines -- and ending the stampede for the emergency exit row -- by introducing mandatory seat reservations.

The Luton-based carrier has gone one step further than its arch-rival Ryanair, which charges for a place in the front row already, by allocating a specific seat for each passenger in trials beginning next year. It stressed that a "large" number of passengers on trial flights would not have to pay but admitted it would charge for choice spots, such as the first few rows and seats over the wing.

EasyJet's chief executive, Carolyn McCall, would not be drawn on the cost of the best seats. "We are trialling how we can board in the most efficient, simple way," she said. EasyJet's speedy boarding programme, where in exchange for a 13 pounds payment passengers can jump the queue, provides some clues as to the likely cost for premium seats.

An easyJet spokesman said the airline would allocate blocks of seats to family bookings "wherever possible", although the airline must give its booking system a multimillion-pound overhaul first.

"A family that books together will sit together where we can arrange it," he said. He said there would be a "band" of prices for the routes that are selected for the trial. "We will work out what seats are most attractive and at what price level."

EasyJet's largest shareholder, Sir Stelios Haji-Ioannou, continued his war of words with the easyJet board when in a critique of the results he warned that pre-allocated seating would "destroy shareholder value."

The trial is a significant shift for an industry that prides itself on keeping things simple. Even for a business as cut-throat as the low-cost airline industry some principles are sacrosanct and they include having unallocated seating because it allows planes to load and disgorge their passengers more rapidly.

If an Airbus A320 jet costs easyJet US$85 million (54 million pounds), the airline believes it is wasting that considerable investment if the aircraft is not deployed as much as possible. Hence the quick turnaround times at uncrowded airports favoured by the likes of Ryanair.

But airlines such as easyJet and Ryanair are under constant pressure to try new ruses that cover rising fuel costs, while avoiding the PR pitfall of simply raising ticket prices and tarnishing the "low-fares" reputation that is the cornerstone of their business models.

EasyJet underlined the impact of fuel costs in annual results, as the cost of flying a passenger rose 3% to 51.30 pounds per journey. Over the same period revenue from add-ons such as baggage check-in fees and speedy boarding rose from 571 million pounds to 719 million pounds and now accounts for more than a quarter of turnover. Pre-tax profits rose by 60 million pounds to 248 million pounds.

One former budget airline executive said the seating move underlined how the brash former upstarts of the aviation world were becoming mainstream players by targeting business travellers.

John Strickland, an industry consultant and a former employee of the now-defunct Buzz carrier, said: "By offering free seating you don't have people clogging up the aisles wanting to find a particular seat. But if easyJet wants to get more business customers and improve its reputation for service, this is certainly something that business customers have been asking for." Nearly 20% of easyJet's passengers, or 9.5 million people a year, use the airline for business trips.

The announcement is a rare example of low-cost airlines reverting to the behaviour of the legacy carriers that they have supplanted on many routes. EasyJet and Ryanair are the progeny of Herb Kelleher, the founder of no-frills air travel and former chief executive of Dallas's Southwest Airlines, who ran his airline on four cardinal rules: fly one type of plane to cut engineering costs; keep overheads down; turn around aircraft quickly; abandon air miles schemes. There have been signs of a shift away from those principles in recent years, with Ryanair announcing that it is talking to Russian and Chinese manufacturers about adding more planes to its Boeing-dominated fleet, while both airlines use expensive airports such as Madrid Barajas that were previously the preserve of traditional carriers.

A Ryanair spokesman said the airline had no plans to extend its reserved seating programme to the entire plane, but it expects to offer bookable seats on a wider number of routes from next year. Under the Ryanair regime, some routes such as Dublin to London Stansted charge passengers 10 pounds each for the right to reserve seats in the front two rows or emergency exit rows. "It looks like we will extend it further within the next few weeks because we are happy with how it has gone."