The Taoiseach, Mr Ahern, is planning to visit the site of the Omagh bombing on Thursday, six months after he was criticised for failing to attend a ceremony to mark the fifth anniversary of the attack.
But the main group acting for victims of the bombing will not be in attendance when Mr Ahern visits the Garden of Remembrance in the town because its members will be in Dublin for a meeting with the Fine Gael leader, Mr Enda Kenny, and the Irish Council for Civil Liberties.
In addition, the Omagh Victims Group confirmed it planned a High Court action for an order to compel the Government to allow the questioning by the PSNI of a Garda informant.
The informant was central to the Nally investigation, which found allegations that the Garda failed to pass information to the RUC that could have prevented the bombing to be without foundation.
The group's chairman, Mr Michael Gallagher, said the decision against meeting Mr Ahern was not a form of protest at his failure to attend the anniversary ceremony last August.
"The group is not into getting involved in stunts," he said. "We envisaged a sit-down meeting with the Taoiseach. We have been told that the longest opportunity to meet the Taoiseach would be for five or 10 minutes."
Mr Gallagher said the group was consulting barristers with a view to taking a High Court action in Dublin against Mr Ahern and the Minister for Justice, Mr McDowell.
The group also plans an action in the Belfast courts for an order compelling the Northern Ireland authorities to do more to secure access to the informant.
The action will be taken against Northern Secretary Mr Paul Murphy, Security Minister Ms Jane Kennedy and the PSNI.
