Fine Gael leader Enda Kenny called on the Government to use whatever measures necessary to ensure an ongoing air service between Shannon and Heathrow.
Mr Kenny was speaking in Co Clare this morning after he met business and tourism leaders angered by the Aer Lingus decision to end its Shannon-Heathrow service.
Almost four weeks after the airline announced its controversial plans, Mr Kenny - on his first official business since the summer recess - held the meeting to discuss the impact of the Aer Lingus move to end the service.
He said that the Government had maintained a stake in Aer Lingus to ensure that the State's strategic interests are protected.
"If the Government is not going to use its shareholding to protect what it said it would protect, then what is the purpose of retaining its 25 per cent stake?" he asked.
Mr Kenny called on the Government to immediately tell Aer Lingus that it supports the holding of an EGM of the company's shareholders to review its decision.
"If the Government fails to act in this case, and if this principle is accepted now, there will be nothing to prevent Aer Lingus management transferring slots from Dublin or Cork to airports outside the country in the future," Mr Kenny warned.
Last night, mayors representing almost one million people in the west called on the Government to use its 25 per cent share of Aer Lingus to reverse the company decision to end the Shannon-Heathrow route.
Mayor of Limerick Cllr Kevin Sheahan said he would have no hesitation in supporting civil disobedience to force the Government to intervene.
The Atlantic Connectivity Alliance lobby group, set up after Aer Lingus decided to drop the Shannon routes to Heathrow, welcomed Mr Kenny's support for the campaign to retain the slots.
Vice chairman of the body, Ken Sullivan, said: "The campaign to overturn this decision is now mounting day by day and will not relent until we have succeeded."
The group confirmed its acceptance of an invitation to meet Minister for Transport Noel Dempsey at Government buildings next Wednesday.
"We welcome this face to face meeting with the Minister and will be taking this opportunity to leave him in no doubt as to the seriousness of the impact that this decision will have on the region, of our dismay over Government inaction on this issue and its apparent inability to understand the grave repercussions this will have for a huge portion of the country," Mr Sullivan said.