The Department of Transport is expected to ask the Garda within days to investigate the leaking of a confidential Government memorandum concerning Aer Rianta to the Labour Party leader Mr Pat Rabbitte.
It is believed in Government circles that the leak, which revealed that the Minister for Finance argued that the drawing up of legislation to break up Aer Rianta is "premature", involved a criminal offence under the Official Secrets Act. A spokesman for Mr McCreevy insisted last night that he fully supported the Government decision to proceed with the break-up of Aer Rianta, but he wanted some complex issues resolved before the legislation, currently under preparation, was finalised.
However, the memo states: "The Minister for Finance therefore considers that the drafting of heads of a Bill and the introduction of legislation at this stage is premature and, accordingly, is not in agreement with the decision sought. The drafting of legislation should be done when all issues are resolved."
However, the Cabinet decided last month to proceed with the drafting of the heads of a Bill.
The Secretary General of the Department of Transport, Ms Julie O'Neill, was working yesterday to ascertain precisely how many copies of the memo were circulated and to draw up a list of everyone who received one.
The revelation that the Minister for Finance opposed the proposal to draw up the legislation now is embarrassing for the Government in the light of its decision to proceed against this advice.