Garda Richard Fallon was shot dead by paramilitary bank robbers on Arran Quay in Dublin in April 1970, just weeks before the Arms Trial got underway.

Nobody has ever been convicted of the murder and the Fallon family has campaigned for years to have a tribunal of inquiry set up to establish what happened. They have unearthed evidence that illegal arms consignments linked to the murder were smuggled into the country with the knowledge of some senior Fianna Fail figures, including former taoiseach Charles Haughey.

In 2001, papers on Richard Fallon's murder, which were to have been released under the 30-year-rule, were removed from the National Archives Office on foot of a certificate agreed by officials in Bertie Ahern's office.

Richard Fallon's brother Martin, himself a garda, was last week claimed to have told Enda Kenny and Fine Gael's Jim Higgins that he had seen Ahern take the case of cash through the VIP section of Dublin airport on his way to catch a flight to Manchester. His family deny attempts to suggest that their fight for justice for Richard Fallon undermined the credibility of Martin Fallon's allegations.

"I would have no reason to disbelieve my uncle's story, " said Finian Fallon, Richard Fallon's son. "I would be saddened if, as you suggest, there appear to be unattributable, concerted efforts to discount my uncle's story.

If this was true, then this would be a continuation of the kind of abuse of political power and cover-up that prevailed at the time that my father was killed, at great human cost."

Fianna Fail continues to claim that the allegations are part of a dirty-tricks campaign to discredit Ahern.

However, Fine Gael strongly insists that Enda Kenny was not the source for the newspaper stories.

A party spokesman confirmed that Kenny did have a "brief chat" about the Fallon claims with the editor of the Sunday Independent Aengus Fanning last Saturday when the two men bumped into each other in Dublin.

Jim Higgins, now a Fine Gael MEP, had, however, earlier that day given the newspaper a statement about the allegations.