The legislation providing for the break-up of Aer Rianta has been described as little more than a "face-saving exercise" that will boost the share price of Ryanair.
The president of SIPTU, Mr Jack O'Connor, said the main effect of the State Airports Bill published today, will be to strengthen the position of Ryanair in its ongoing battle with Aer Rianta airports.
Despite appearing to contain provisions guaranteeing no diminution in pay and conditions for Aer Rianta staff, Mr O'Connor warned that workers will suffer if the semi-State company is broken up.
The long-awaited publication of the legislation, which was first announced last July, was welcomed by Ryanair's chief executive, Mr Michael O'Leary.
"No one in Irish tourism should feel any regret at getting rid of the Aer Rianta monopoly or the Board that has run it so badly for the last 10 years," Mr O'Leary said.
He again called for work to begin on the proposed new airport terminal for Dublin.
Fine Gael transport spokesman Mr Denis Naughten said the Bill effectively transfers responsibility for restructuring Aer Rianta to the Minister for Finance.
"Passing Aer Rianta around from one member of Cabinet to another does not represent any progress on the issue, and only delays the process even further," Mr Naughten said.
The decision to defer the break-up of the company until the middle of next year was undermining Aer Rianta, the Longford Roscommon TD said.
"The big losers are the Irish aviation industry and, in particular, the taxpayer. This continuing uncertainty was a major factor behind the losses at Aer Rianta and its subsidiaries in 2003," he added.