The Tánaiste revealed that she rejected a demand that 40 per cent of Aer Rianta be privatised.
Ms Harney said that a few years ago the chairman of the company had told her the proposal had the unanimous agreement of the board, including the worker directors.
"At the time I did not agree because it would have converted a State monopoly into a private one."
Defending the Government's proposal to break up Aer Rianta, Ms Harney said it was simply seeking to put in place the best regime to drive competition and business at all airports.
"I do not know how many misunderstanding could have arisen in the part of the trade unions. The social partnership talks dealt with this matter for some considerable time. I was party to those talks until 5 a.m. on Friday, and no one could have been in any doubt as to the Government's legislative plans."
Ms Harney was replying to the Labour leader, Mr Pat Rabbitte, who asked who was driving the campaign for additional terminal capacity at Dublin Airport.
He referred to remarks made in the Seanad on Tuesday by the Leader of the House, Mrs Mary O'Rourke, who had asked how one person could have got his own way, and raised the question of his party alignment.
Mrs O'Rourke, he added, said she had received information rendering her quite speechless about substantial donations made by the gentleman in question.
Ms Harney said she did not know what Mrs O'Rourke was talking about. However, Mr Michael O'Leary, of Ryanair, had announced in many fora that he had voted for Mrs O'Rourke's running mate in the last election in the Mullingar area.
Mr Rabbitte pressed the issue of donations, adding that the Tánaiste should find out about the matter, and make her position clear to the House.
Ms Harney said that any donations given by any individual or corporation were subject to public disclosure.
"It is a well-known fact that Ryanair gave a donation to the Progressive Democrats, which was published along with donations to other political parties of which the limit is €5,000."
She said the terminal had not proceeded because the then line minister did not agree with competition at Dublin Airport.
"I hope it will now proceed on the basis of the Government's policy programme. At issue are the interests of tourism, the regions and the three airports.
"Under one umbrella, it is not possible for Shannon Airport, in particular, and Cork Airport to a lesser extent, to reach their full potential. Local autonomy, where local boards can enter into agreements with airlines to bring more services and passengers to the airports, is needed. For every one million passengers brought in, 1,000 more jobs will be created."
