The Northern Ireland Affairs Committee is today to publish a report into unanswered questions surrounding the Omagh bomb atrocity.

MPs have carried out the Parliamentary probe into claims that spy agencies failed to pass on evidence about bombers in the days after the atrocity that killed 29 people and two unborn children.

It follows a review, commissioned by Prime Minister Gordon Brown and carried out by Intelligence Services Commissioner Sir Peter Gibson, into the allegations that the Government hoped would put an end to the speculation.

Members have heard evidence suggesting that arrests could have been made quickly with earlier exchanges of information. There were claims that GCHQ monitored conversations involving several mobile phones and a telephone kiosk on the day of the blast.

Detectives also spent several months trawling through 6.4 million phone records to identify likely numbers which it is believed could have been made available to them within a day of the August 1998. The committee is expected to report on the issue of how information is passed between intelligence agencies and police teams.

The influential committee has had a number of official doors slammed in its face while trying to discover if claims that GCHQ, the top-security listening post, had made transcripts of mobile telephone conversations between the bombers on the day of the attack and whether that information was passed on to the RUC team investigating the blast.

That led to difficulties during the Parliamentary evidence sessions with some witnesses unable to even confirm the existence of any intercept evidence.

In a BBC Panorama programme last year claims were made that the identification of a specific phone number gave Special Branch a “nugget”, which it passed on to GCHQ and requested it carried out ‘live’ monitoring. It went on to claim that if GCHQ had picked up the phone’s movement from the Republic of Ireland towards Omagh, and phrases such as “bricks are in the wall”, which had been used in previous bombing incidents, were picked up, then it could have been possible for the monitors to see a bomb run in progress.

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

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