Aer Lingus has complained to the Advertising Standards Authority (ASA) about Ryanair advertising that it said inflated Aer Lingus fares.
The advertisement in question claimed the State airline's average fares were €185.86, a figure that the carrier's chief executive, Mr Willie Walsh, dismissed yesterday as a "bizarre and basic financial miscalculation".
According to an Aer Lingus statement, the Ryanair ad calculated the State carrier's average fare by dividing total sales for 2002 by that year's passenger numbers.
But the figure included non-passenger sales generated from from former subsidiaries, which the accounts stated were discontinued operations.
Mr Walsh wrote to Ryanair boss, Mr Michael O'Leary, pointing this out. Mr O'Leary replied by accusing Mr Walsh and his fellow directors of "hiding the passenger figures in their accounts" and said the company could not complain if the accounts gave rise to inaccuracies.
Mr O'Leary arrived into Luton Airport in the UK yesterday in a second World War tank. British carrier Easyjet was the target of the publicity stunt.
Speaking to a Leinster Society of Chartered Accountants lunch yesterday, Mr Walsh said he would not stay silent when Ryanair misrepresented Aer Lingus financial information.
"The advertisement is obviously untruthful and grossly misleading," he said.
He added that if Ryanair's figures were correct, Aer Lingus would make profits of €700 million this year. "We're not quite that good yet," he said.
Meanwhile, Mr Walsh told reporters that Aer Lingus would decide in September whether Boeing or Airbus would deliver the largest order every likely to be taken by the airline.
Aer Lingus plans to buy 40 planes for its short-haul fleet. The cost is likely to be in the region of €1.6 billion.
The airline plans to standardise the craft it uses on flights to the UK and continental Europe. The move is part of a strategy to re-invent the airline as a low-cost, no-frills carrier.
Low-cost airlines typically use just one type of craft on their routes as this helps them to achieve savings. Currently, Aer Lingus uses a variety of Airbus and Boeing craft.
During his speech, Walsh said that the company was encouraged by its performance in the first four months of 2003.
"Our traffic grew during this period on the transatlantic by 19 per cent and on Europe by 35 per cent compared to last year," he said.
He added that the airline had increased capacity by 18 per cent on transatlantic routes and 17 per cent on European routes.
But Mr Walsh warned the war in Iraq and the SARS scare would contribute to a very difficult 2003 for the industry.