Unions at Dublin Airport are to meet today to decide on whether to take industrial action over the proposed break-up of Aer Rianta.
The meeting follows the rejection last month by the Minister for Transport, Mr Brennan, of a request for a third party review of his plans to break up Aer Rianta into three separate airport authorities.
It also comes amid increasing pressure for action from the workers in Dublin, Cork and Shannon airports, after they voted overwhelmingly last month for industrial action.
This also included members of Aer Rianta's middle management levels who, as members of Impact, voted eight to one in favour of industrial action.
Today's meeting involving officials from SIPTU, Impact, Mandate and the Technical Engineering and Electrical Union (TEEU) will discuss what potential action the unions could take.
This includes the possibility of one-day stoppages, which could lead to the closure of one or all of the airports on a temporary basis.
Mr Arthur Hall of the TEEU said there was "tremendous pressure on the ground for action from workers" for a decision at the meeting to take industrial action. He described last month's letter from the Minister as "a slap in the face to everybody".
A spokesman for the Minister said that while Mr Brennan intended to proceed with the break-up of the airport he has ensured unions there are no proposals for redundancies as part of the restructuring.
Mr Michael Landers of Impact said he could provide "no guarantees" at this stage as there were no business plans in existence for the future of the airports.
He said that the Ministers' proposals "have implications for our members" and that there was concern about the threat of the break-up of Aer Rianta "to jobs and job security".