Four men were still being questioned by police in Antrim last night following Wednesday night's discovery of what the PSNI described as "an incendiary bomb-making factory" in a housing estate in Strabane, Co Tyrone.
Detectives investigating the discovery of six fully-primed cassette incendiary bombs in a ground floor flat at Lisnafin Park have linked the find to the 'Real IRA'.
Three men were arrested in Strabane and a fourth in the Waterside area of Derry after bombs and bomb-making materials were found when police searched the flat after they had received reports about suspicious activity in the area. The devices were removed from the scene by forensic officers who later carried out further searches of the area. Nothing else was found during the subsequent searches.
A PSNI officer at the scene, Acting Insp David Hall, said the discovery of the incendiary bombs had prevented fire damage being caused to properties in Strabane.
"These incendiary bombs were ready for use but aside from that, to have stored them in the ground floor of a block of flats showed a total disregard for the lives of other people in the flats."
Meanwhile the Chief Constable of the PSNI, Mr Hugh Orde, said that the police had uncovered a bomb-making factory which he linked to dissident republicans.
"Anyone who tries to make any sort of a device in a built-up area is taking extreme risks with other peoples' lives.
"We have recovered what we would say is a major bomb-making factory and as a result of that, the people of Strabane are a lot safer," he said.
Local SDLP Assembly member, Mr Eugene McMenamin, said the discovery was made as a meeting of the town's District Policing Partnership was taking place.
"Those responsible for making such devices and for storing them in the middle of a housing estate must get a grip on themselves and must also get a grip on the fact that they are rejected by the overwhelming majority of people in Strabane."