A BBC investigative programme says it has uncovered evidence that phone calls made by the Omagh bombers on their way to plant the bomb, were being recorded by the UK's electronic surveillance agency.
The BBC's Panorama programme says that an RUC Special Branch officer passed the phone number of a leading dissidant republican onto the GCHQ agency and asked that all calls be monitored weeks before the bomb.
The disclosure has led to new calls for a public inquiry into the bombing.
According to the Panorama programme to be broadcast tomorrow night, at least one of the Omagh bombers phones was being monitored by a secret British surveillance agency on the day of the atrocity.
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, Gardai 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.
