Workers at Aer Lingus may demand that the company review its cost-cutting business plan in the light of the resignation of its three top executives, a union leader warned last night.

However, Mr Michael Halpenny, national industrial secretary of SIPTU, said it was too early to be definitive about the unions' response to the resignations, which he described as a "bombshell".

Mr Halpenny said unions had, from the outset, questioned the need for job cuts on the scale proposed by the company, and now the authors of the three-year business plan were not going to be around to see it through.

Asked if unions would now demand that the plan be shelved or revisited in some way, he said: "I imagine our members will be asking us to do that.

"It is too early to be prescriptive about anything, but lots of questions are going to be asked once people have caught their breath."

Mr Halpenny said the three men were entitled to make the decision they had and he was not criticising them as individuals. However, he was surprised by the move.

"They [ the three executives] were looking for the commitment of the workforce to a three-year business plan and now we have a situation where they are walking away."

The unions would "obviously prefer" if there was now a review of the business plan, which provides for 1,325 redundancies, about one-third of the airline's workforce.

As well as job cuts on that scale, the unions had made clear their opposition to outsourcing, "which is basically taking our members' jobs and replacing them with cheap labour", he said.

Mr Halpenny said the latest development underlined the fact that, apart from the State as shareholder, unions and their members remained "the only constant" in the national airline.

One employee claimed last night that there was general relief among workers that the three men were leaving.

The employee said staff had serious reservations about a number of moves which Mr Walsh and his team initiated. These included the level of job cuts, the outsourcing of "almost everything" and the abolition of business class on many routes.