Man is held over blast at Palace Barracks in Holywood
Police were last night questioning a 60-year-old man arrested in connection with a bomb attack on MI5's Northern Ireland headquarters.
Dissident republicans were blamed when a small explosive device detonated in the back of a post van at Palace Barracks in Holywood last August 14.
While no one was injured, a fire broke out in the van and spread to vehicles and three garages.
The man was detained in Greater Belfast yesterday morning.
Palace Barracks has previously been targeted by dissident republicans when a bomb exploded outside the base six years ago.
Around 1,000 MI5 operatives work in the base, making it the national security agency's largest headquarters outside London.
In April 2010, between 40lbs and 50lbs of explosives hidden in a taxi were detonated outside the front gates. An elderly man suffered minor injuries in the blast and the base was evacuated.
An investigation found security cameras planted in trees outside.
It's believed the recordings were being used to target soldiers and build profiles of MI5 agents.