A new investigation must be set up to examine whether the state withheld vital intelligence from detectives hunting the Omagh bombers, a parliamentary report said today.

The parliamentary probe looked at claims that spy agencies failed to pass on crucial evidence about bombers in the days after the 1998 atrocity.

Twenty-nine people and two unborn children died in the Real IRA attack.

Today’s report by the Northern Ireland Affairs Committee also said too many questions remained unanswered over how much the security services knew about the bombers’ movements.

Speaking today, Victor Barker, whose 12-year-old son James was killed in the bombing, said he was not surprised by its findings.

“This is what we’ve suspected all along — that information was being hidden from us,” he told the Belfast Telegraph.

“There should be a proper, public inquiry with full access to all the information, because we need to know if there was some form of directive or conspiracy to make sure these people weren’t brought to justice. In 12 years two people have been charged and not one has been found guilty, and I find it absolutely amazing that this investigation was botched up in the way it was.”

In January 2009 a report by Intelligence Services Commissioner Sir Peter Gibson rejected claims that vital intelligence about the bombing was deliberately held back.

But the committee today said that Sir Peter’s report left many crucial questions unanswered about the way the atrocity was investigated.

Members said they were disturbed by suggestions that arrests could have been made quickly if there had been earlier exchanges of information.

In 2008 the BBC’s Panorama programme claimed that intelligence agency GCHQ monitored suspects' mobile phone calls as they drove to Omagh from the Republic on the day of the bombing. Panorama said this information was never passed to detectives assigned to the case.

Although the programme’s claims were later rejected by Sir Peter, today’s report claims the victims’ families still need answers.

“Far too many questions remain unanswered,” committee chairman Sir Patrick Cormack said.

The committee looked at how information is passed between intelligence agencies and police and called for details about what Special Branch knew to be revealed.

“We are particularly concerned by the suggestion that the names of individuals who owned telephones, thought to have been used in the bombing, were known to the intelligence services or to the police,” the report states.

“We seek a definitive statement from the police of whether such names were known. If they were, we seek an explanation of why no action was taken to arrest or question the owners of those telephones.”

The committee says questions remain about whether the bombing could have been pre-empted if action had been taken against the terrorist gang who carried out a spate of bombings prior to Omagh.

While dismissing the possibility that the bomb could have been prevented, Sir Peter said he could not rule in or out the possibility that ‘live’ monitoring occurred.

The committee also criticised the Government for refusing to give it sight of Sir Peter’s full report, which has been classified for security reasons.

That provokes speculation which is “not conducive to convincing us that everything that could be done has been done”, the committee said, adding it was exasperating.

Sir Patrick, the committee chairman, added that key questions remain unanswered.

“The criminal justice system has failed to bring to justice those responsible for the Omagh bombing,” he said. “The least that those who were bereaved or injured have the right to expect are answers to those questions.”