A man was arrested today in connection with a 500lb car bomb abandoned near a busy motorway in Co Down.
The 26-year-old suspect 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 opposed to the peace process.
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.