Security sources in the North believe Republican dissidents were behind an attempt to lure members of the RUC into an elaborate boobytrap bomb attack in the Co Derry village of Claudy.
Yesterday, following what the RUC described as "a sensitive and highly dangerous operation" British army technical experts made safe a 100 lb booby-trap bomb which had been planted at a security gate at the rear of the village's police station.
The massive device, of home-made explosives, had a power pack and booster tube attached and had been packed into a plastic barrel.
The bombers cut their way through a chain-link fence behind the police station before planting the device at the inner security fence gate. They had attached fishing line to the gate and to the bomb in the hope police officers leaving the station would trigger it.
"If this bomb had gone off, the blast would have been lethal," said Chief Insp Bob Moore.
"Anyone within a distance of 30 metres would have been killed or injured."
More than 60 houses were evacuated by the security forces, and hundreds of residents were forced to stay with friends or relatives until they were allowed back into their homes yesterday evening.