Omagh campaigner Michael Gallagher, whose 21-year-old son Aiden was murdered in the bombing, said today’s Special Criminal Court ruling came as a further blow to bereaved families.
His comments come in the wake of the acquittal of Colm Murphy on charges relating to the 1998 bomb.
Mr Murphy (57), the only man ever to be convicted over the atrocity, was today cleared of conspiring to cause the explosion after a key piece of evidence was ruled inadmissible.
Mr Murphy was originally jailed for 14 years by the Special Criminal Court in 2002 but had his conviction quashed by the Court of Criminal Appeal quashed in 2005. Today's ruling brought to an end his retrial.
Mr Gallagher said: “It has been the history of this process that the families have been disappointed time and time again, but when it happens it is still hard. But I think this is the first time in years I feel angry.”
He said of the Omagh attack: “These people seem to be so elusive to authorities on both sides of the Border.
“This is a crime that the Taoiseach, the [British] prime minister and the president of the United States took an interest in.
“If this can’t be solved what hope is there for other crimes?” Mr Gallagher said that, despite the authorities pledging no stone would be left unturned in the search for the killers, the families believed that the only satisfaction they had received was through their own civil case.
“We have had empty promises both publicly and privately from government ministers,” he said. “I feel that, even more than ever, there is a justification for a full cross-border public inquiry so the families can get closure. That is the least the governments can do for us.”
Fine Gael leader Enda Kenny said the dismissal of the case "will come as a huge disappointment to the families of the victims of this atrocity who have campaigned so long for justice on behalf of their loved-ones".
“The situation now is that nobody stands convicted of the largest single terrorist attack in Northern Ireland. While getting a successful prosecution at this stage will be very difficult, I would urge the security services on both sides of the Border to continue to co-operate on this case," he said.
A spokeswoman for Garda Commissioner Fachtna Murphy declined to comment on the retrial collapse but added: “The resolve to tackle dissident republican activity remains as high as ever.”
Additional reporting PA