It is understood, however, that the minister for transport Noel Dempsey has received legal advice from the Attorney-General Paul Gallagher that the airline is on solid legal ground.

It is believed, however, that Dempsey was not consulted by the airline on its unprecedented decision to reject the EGM request from its largest shareholder.

It is understood that Aer Lingus will seek a High Court injunction against any move by Ryanair to hold an EGM without the board's consent as it theoretically could do under Irish company law.

An aviation analyst with Davy Stockbrokers, Stephen Furlong, said that it was crucial that Aer Lingus won the battle to transfer its Heathrow slots from Shannon to Belfast.

He said that the Belfast base was part of wider restructuring programme that the airline's board had to deliver on if was to retain investor confidence.

"Management's credibility and authority is on the line on this. It's obviously not going to be easy, as they are up against some powerful constituent bodies, but cost cutting is necessary, " he said.

"If they can't deliver, no serious investor will touch Aer Lingus."

Meanwhile, the airline has defended it decision to allocate the maximum possible profit sharing payout for the first half of this year to its employee share ownership trust (ESOT), which will play a crucial role if it is eventually forced into an EGM.

Despite the airline's pretax profits slumping by 42% to 2.6m and widespread industrial unrest, the ESOT will receive 1.6m, the equivalent of around 450 per member. The payment will be made at the end of the year.

However, the airline's finance director Greg O'Sullivan said that the move had not been designed to curry favour with the ESOT.

"You have to accrue that sort of figure for the first half of the year. You don't want to understate it, " he said.