Allegations that the Garda Síochána failed to pass on information to the RUC that could have prevented the Omagh bombing are without foundation, according to a high-level investigation.
Led by a former senior civil servant, Mr Dermot Nally, the group concluded that charges leveled by a Donegal-based garda detective sergeant did not stand up to scrutiny, the Minister for Justice, Equality and Law Reform, Mr McDowell, told the Dáil last night.
However, it emerged last night that the Nally committee did not question Det Sgt John White's alleged informer, Mr Pat Dixon, who has claimed in the past that he infiltrated the "Real IRA".
Det Sgt White had alleged that the Garda could have prevented the bombing if it had passed on information to the RUC about stolen cars used in the August 1998 attack on the Co Tyrone town, which claimed 31 lives.
He also alleged that the Government subsequently struck a deal with the "Real IRA", promising immunity from prosecution if it carried out no further attacks, and that Garda officers had committed criminal acts.
The Nally committee, which also included a former secretary of the Department of Justice, Mr Joe Brosnan, and the former director of public prosecutions, Mr Eamon Barnes, first met in April 2002 and met 62 more times.
During the inquiry the committee interviewed 25 people, some more than once, including Det Sgt White, who is currently under suspension and facing criminal charges on an unrelated matter, said Mr McDowell.
The committee met the Northern Ireland Police Ombudsman, Ms Nuala O'Loan, just once. She passed on a 58-page document detailing Det Sgt White's allegations, along with some corroborative evidence.
It failed to secure an interview with Mr Dixon.
Describing this as a major omission, the Fine Gael leader, Mr Enda Kenny, said the report failed to explain why it could not have done more to secure an interview with him.
Mr Dixon, who alleges that he worked as a Garda informer inside the "Real IRA" for the eight months before Omagh, refused to co-operate on legal advice.
However, The Irish Times understands that Mr Dixon, who has described himself as a master car thief, has indicated that he might change his mind in future.
Mr Kenny criticised the committee for failing to meet Ms O'Loan again before concluding its investigation. "We presented a document and heard nothing more," her spokesman confirmed last night.
In his carefully worded Dáil statement, the Minister for Justice said he could not publish the report, which is more than 100 pages long, because it would endanger national security.
He would be happy to publish it in other circumstances, he said. "It is a particularly lucid and compelling document, and I believe that, if people had access to it, few if any would dispute its conclusions."
His refusal, however, is set to provoke outrage among the families of the victims, who are now suing five men, including the jailed "Real IRA" leader, Michael McKevitt, suspected of orchestrating the attack.
The most persistent allegation, Mr McDowell said, has been that the Garda failed to pass on information that could have prevented the bombing. "It is hardly necessary to spell out the grave implications of that if it were true," he said.
This allegation has been repeated in the media, but the Minister said no such allegation had in fact been made directly to the Nally committee, although some sources disputed this point strongly last night.
Quoting from the report, he said the central charges were that a senior Garda officer would have been prepared to let a car stolen in Dublin cross the Border in order to protect the alleged informer, Mr Dixon. Det Sgt White also alleged that the RUC was not told that the "Real IRA", which had first tried to steal a car in Dublin, had managed to get one elsewhere the night before the bombing took place.
Ruling out a public inquiry, the Minister said: "There are no grounds for such an inquiry, and any repetition of unfounded allegations will not change that situation".