The Fine Gael finance spokesman was asked to leave the ESRI building when he tried to attend yesterday's press conference.
"My nose isn't out of joint," Mr Richard Bruton said later, after a member of the ESRI staff told him the press conference was for journalists only. "It's fair enough. I just went along thinking it was open."
Mr Bruton arrived at the institute's office on Burlington Road, south Dublin, shortly before the briefing on its mid-term review of the National Development Plan.
Before he took a seat, a member of the institute's staff asked him to leave.
It is unusual, but not unheard of, for politicians to attend press conferences. The Fine Gael health spokeswoman, Ms Olivia Mitchell, and her Labour counterpart, Ms Liz McManus, took prominent seats at the Government press conference in June at which its health reform package was published.
Also this summer, the Green MEP Ms Patricia McKenna was revealed to have attended an EU summit in Greece as a "journalist" with the Socialist Worker newspaper, published by the Socialist Worker movement, a rival party.