Forensic tests on the remains of the bomb which exploded underneath Hammersmith Bridge in London have confirmed that its timer was identical in manufacture to a device found by gardai in a search of a house in Dublin on May 25th.
The "timer power unit" (TPU) found in Ballyfermot was manufactured by the "Real IRA", which was responsible for the August 1998 Omagh bombing.
Forensic examination of the remains of the bomb at Hammersmith was concluded last weekend and there was a positive match with the device found in Ballyfermot. It has been designated a "Mark 19" TPU.
The previous TPU "marks" were all manufactured by the Provisional IRA prior to its last ceasefire in August 1997. The latest device is seen as a refinement of the Provisionals' TPUs and is said by security sources to be as good as anything manufactured by the IRA.
The "Real IRA" also has access to a source of electrical detonators. The find in Dublin included plastic explosive and electrical detonators.
It is understood the "Real IRA" sent a unit to England about two weeks before the explosion at Hammersmith. The disappearance of a number of known activists prompted the searches and series of arrests in the Border area and Dublin immediately before the bombing in London. Some 13 people were arrested but all were released without charge after questioning.
The Garda believes there is now collusion between the "Real IRA" and the other splinter republican terrorist organisation, the Continuity IRA, at leadership level.
The "Real IRA" is said to be refining its skills and tactics, and has carried out a number of mortar attacks on security bases in Northern Ireland which are seen as practice runs.
It is not known if the "Real IRA" unit which travelled to Britain intends to stay there to carry out further attacks or if it was merely on a test run to see if it could evade Irish and British security checks.