O'Leary said that the current proposal, which was approved by An Bord Pleanala last month, will lead to a doubling of passenger charges at the airport, which would force Ryanair to act.

"We have to keep it under review. The aviation regulator here has confirmed that if the present Dublin Airport plan goes ahead, passenger charges are going to double, " he said.

"If passenger charges at Dublin double over the next couple of years, there is no doubt that traffic is going to be significantly hit, particularly during the off-peak winter period. And that will lead us to ground aircraft."

The low-fares airline has already decided to ground planes at Stansted airport in London after airport charges there were doubled earlier this year. The airline will suspend around 20% of its services from the British airport . . . its main base . . . this winter.

O'Leary said, however, that there was no question of grounding flights at Dublin this winter. "It's not this winter but it depends on what happens with airport pricing in Dublin over the next year or two."

"The decision is going to become a fait accompli if they are allowed to waste 800m on a terminal that should only cost 200m."