Aer Lingus was plunged into further crisis today as the former state-owned airline said its chief executive will be leaving immediately.

In a boardroom putsch, Dermot Mannion, the man who took over at the Irish flag carrier from British Airways' Willie Walsh, was pushed out by Irish aviation industry veteran Colm Barrington who came in as chairman last year.

The departure of Mannion - who joined Aer Lingus from Emirates four years ago - comes after a huge row in which Aer Lingus was accused of lying about its trading outlook when it was fighting off a hostile takeover from Ryanair at the end of last year.

The Irish airline, in common with all its European full-service rivals, has been struggling during the global aviation recession.

Barrington is taking immediate executive control of the airline ahead of the search to find a replacement.

"It appears Barrington is saying that change is needed and that he is after a tougher chief executive," said one senior industry source.

"Mannion is a considered individual with a consensual style. It should be remembered he saw off two unsolicited approaches from Ryanair and that he saw through the initial public offering of the airline out of state hands."

The departure of Mannion comes after a hastily convened meeting of the Aer Lingus board at the end of last week.

That meeting followed a rough few weeks for the Aer Lingus board.

The executives had been on an investor roadshow in which they are understood to have been attacked by major shareholders for a reversal in trading guidance at its annual results which saw a 26% collapse in Aer Lingus's share price on the day.

Ryanair's Michael O'Leary said that the reversal of guidance showed that Aer Lingus's board had lied during its latest takeover battle.

Aer Lingus posted a €17 million (£15.7 million) loss for 2008 but warned that 2009 will be even worse, and it would therefore miss its City forecasts.

Those losses appeared to contradict comment by Aer Lingus before Christmas when it was fending off that €700million takeover bid by Ryanair, which owns almost 30% of the carrier.

Aer Lingus said in its defence document: "We expect Aer Lingusto continue to enhance profitability in 2009 and beyond."