A man was arrested today in connection with a 500lb car bomb abandoned near a busy motorway in Co Down.
The suspect (26) is being questioned about the device left at the A1 bypass in Newry last Thursday.
He was detained in the Rostrevor area of Co Down and has been taken to Antrim police station for questioning.
The failed bomb attack has been blamed on dissident republicans.
Police said the bomb, similar in size to the 1998 Real IRA bomb in Omagh that claimed the lives of 29 people including a woman pregnant with twins, could have caused “huge devastation”.
The bomb was discovered in an abandoned van at an underpass in Newry on the main Belfast to Dublin road and was made safe by a British army bomb disposal squad after three days of road and rail disruption. The road was finally reopened on Saturday morning.
Police believe the bombers may have been forced to abandon the device, which was contained in a wheelie bin, because of a security operation taking place in the Newry area at the time. The abandoned blue Ford transit van was stolen in Maynooth, Co Kildare, in January and carried false Donegal registration plates.
On Friday hundreds of motorists, including foreign tourists, unwittingly drove past the bomb after some motorists took away cones that cordoned off the van. This happened when police were not at the scene, the PSNI admitted.
Last night detectives investigating the dissident republican murder of Catholic police officer Ronan Kerr in Omagh, Co Tyrone, were given six more days to question two of three suspects being held.