It is the first time since his retirement 19 years ago that the former taoiseach has made such an endorsement.

"Having worked closely with him in the Institute of European Affairs, I know that he would be a most effective and valuable member of the Dail, " FitzGerald is quoted as saying on flyers being distributed by Regan.

FitzGerald, 80, remains popular with area Fine Gael activists, though it is rumoured he has fallen out with the current party leaders.

The move could give Regan, a barrister and former European Commission staffer, a crucial boost going into the party's selection convention, expected to be held in late March. Fine Gael, which once held two seats in the Dun Laoghaire fiveseater, now has no Dail representation in the area.

FitzGerald this weekend told the Sunday Tribune that his decision to endorse Regan was "personal not political. I've known him a long time and he's an eminent European lawyer".