The families of the victims of the Omagh bombing have demanded that the British government release secret intelligence information which it is claimed was withheld from police investigating the atrocity.
The BBC's Panorama programme says that an RUC Special Branch officer passed the phone number of a leading dissident republican on to GCHQ, thw UK government's electronic monitoring service, weeks before the bomb and asked that all calls be monitored.
Well-placed sources told Panorama that GCHQ was monitoring the bombers' phones that day, a claim confirmed by Ray White, former assistant chief constable in charge of crime and Special Branch for the Northern Ireland police service.
Whether GCHQ could have helped stop the bombing comes down to whether they were listening to live exchanges between the bombers, allowing them to respond to events, or whether they were simply recording the conversations.
Mr White told Panorama that the Special Branch officer responsible for requesting GCHQ's assistance was 'adamant' he had asked for live monitoring.
He said the officer did this 'primarily for the purpose of triggering a pre-arranged surveillance plan' to interdict the bombers.
Weeks before the bombing the GCHQ was given the mobile phone number of a dissidant republican by the then RUC Special branch, and asked to monitor all calls.
The day before the bomb, gardaí alerted the RUC that a device was going to be moved over the border imminently.
GCHQ then tracked calls made from the bomber's phone en route to Omagh and recorded a coded message which meant the bomb was in place.
The information gleaned from those calls was never passed on to the RUC even though it is claimed by both relatives of the victims, and those investigating the bomb, that such information might have prevented the atrocity or helped in bring those responsible to justice.
Today, the families said if the material still existed, it should be made available to them to use in a civil action which is ongoing.
