Speaking at a meeting of EU transport ministers in Luxembourg today, Minister for Transport Martin Cullen said the Government will argue that the takeover would be in breach of EU competition law and limit passenger choice on routes between Ireland and the UK.
Mr Cullen said: "The Government wants to see competition maintained in the aviation services. We do not want to see a new monopoly created in the private sector."
He said: "We believe that would be bad for the development of aviation services."
"There is a multiplicity of services provided by both airlines covering different types of markets. We believe both airlines competing along with other airlines in the marketplace is the best way to develop those services," he said.
At the meeting Mr Cullen defended his handling of the Aer Lingus floatation, saying the Initial Public Offering (IPO) was in the best strategic interest of Aer Lingus.
Fianna Fáil TD, Martin Brady welcomed the news that Government officials would travel to Brussels to discuss the takeover bid.
"Ireland has benefited enormously from having Aer Lingus and Ryanair in direct competition - this is an environment we need and we must not allow one player to take over the market, for the sake of both passengers and aviation workers," the Dublin north east TD said.
But Siptu's National Industrial Secretary Michael Halpenny said: "Not one of the Fianna Fail TDs contacted by Aer Lingus workers over the past few days to seek support for blocking Ryanair's predatory takeover of the national airline has responded with anything more helpful than an acknowledgement."
Mr Halpenny said: "While the Minister for Transport, Martin Cullen, was defending the Government's handling of the Aer Lingus privatisation after a meeting of transport ministers in Luxembourg today and says the Government will argue that a Ryanair takeover of Aer Lingus would breach EU competition law, his colleagues appear to have taken a vow of silence and joined the Trappist order."
"Even those who had voiced concerns in the past over the decision to privatise Aer Lingus are now blindly following the party whip," he claimed.
"SIPTU will continue to campaign against the Ryanair takeover and in defence of our members jobs and working conditions. This abandonment of constituents will not be forgotten come the next election," he said.