The Taoiseach was today discussing the European Parliament's report on the issue of CIA "rendition" flights when he meets parliament president Josep Borrell in Dublin.
Yesterday, Mr Ahern told journalists that he rejected any suggestion that Irish airports had been used by CIA-operated aircraft to illegally transport prisoners.
"Did they ever use Ireland as a base or a hub or a destination? The answer to that is a categorical no," he told reporters.
"In the Oval Office, sitting far closer than I am to you, I looked at President Bush and I said to him: 'I want to be sure to be sure' and he assured me. You can't do more than that," Mr Ahern said.
Minister for Foreign Affairs Dermot Ahern was known to be "livid" and "fuming" about the early release of the report which was due to be published today.
He will meet Mr Borrell tomorrow and is expected to express the Government's "absolute anger" that the report was released two days before he was due to outline Ireland's position to the committee in Brussels.
The draft EU report expresses "serious concern" at the 147 stopovers by CIA-operated aircraft at Irish airports, many of which were coming from or directed to countries linked with "extraordinary rendition".
The Foreign Affairs Minister said yesterday that one of the aircraft that was cited by the report was owned by the Boston Red Sox baseball team and was flown to several Irish regional airports on what he understood was a "golfing expedition".
In the European Parliament yesterday, Labour MEP for Dublin Proinsias De Rossa, who was also on the committee that compiled the report, said: "The Minister is mistaken in his belief that the plane which landed at Knock, and known to have been used by CIA for renditions, is owned by the Boston Red Sox.
"In fact, the plane is owned by Philip H. Morse, a minority partner in the Boston Red Sox franchise. Moreover, Mr Morse confirmed to the Boston Globein March last year that the plane had been leased to the CIA.
"Indeed, the plane which Minister Ahern refers to is none other than the notorious 'Guantanamo Express', known as such because of its repeated trips there."