David McKittrick: Questions remain about intelligence before and after this shocking attack

The Omagh bombing seemed to be an incident which was as straightfoward as it was callous: a 500lb Real IRA car-bomb, placed in a market town on a busy Saturday afternoon, was detonated after a misleading warning.

The initial shock and horror at the multiple murders gave way to other emotions which included sympathy but also a determination to bring those responsible to justice. The authorities vowed that this would be done, but as time went on most of the legal sequels failed to produce convictions. It is technically possible that more prosecutions might be brought, but police admit that this becomes increasingly unlikely as time passes.

As the years went by many wondered about the performance of the security forces and in particular the intelligence agencies, both before and after the attack. It emerged that many of those involved were known to the police and some were under a degree of surveillance.

The answer to the biggest question of all – whether the attack might possibly have been intercepted and prevented – remains unclear.

The BBC Panorama programme on the incident did not claim that the bombing was preventable. Instead, it said that during the bomb run, from the Irish Republic into Northern Ireland, the mobile phones of some of the bombers were monitored by GCHQ, the Cheltenham-based electronic surveillance agency. It asserts that detectives investigating the murders were never told about the fact that interception had taken place and had never been provided with the intercepted telephone numbers used by some of those involved in the bombing.

In his report on the issues raised by Panorama, Sir Peter Gibson refrained from explicitly confirming or denying this. He conceded that the RUC's Special Branch shared intelligence with the force's CID in a "cautious way" but added that he did not investigate why this was so. Sir Peter made no criticism of GCHQ for not passing on telephone numbers to the CID.

The Panorama thesis was that the investigation into the Omagh bomb was hampered, perhaps fatally, by a reluctance to share information and that the opportunity to make early arrests and raids was lost.

According to a senior police officer quoted by the BBC, this assertion, if true, "effectively sabotaged the investigation through the starvation of essential intelligence". Early information would have given an immediate chance "for executive police action to bring the culprits to justice, to search their homes and to recover vital evidence. This opportunity did not arise for many weeks and, in the case of two key witnesses, nine months".

In its report yesterday the Northern Ireland Committee concluded that questions remain about whether the bombing could have been pre-empted and called for a new investigation into whether intelligence on suspects was passed on to investigating detectives. It sought reconsideration of how any intercept intelligence was or was not used. The committee also questioned whether the names of suspects were known "in the days immediately after the bombing, and if so, why no arrests resulted".

Sir Peter, in his report, had no real criticism to make of the various links in the intelligence chain, either singly or collectively. But the Northern Ireland Committee, far from being reassured, has concluded that in his findings many crucial questions remain unanswered.