Heavily-armed police on Tuesday arrested a man north of Melbourne on suspicion of possessing items used to make bombs.
Arson and explosives squad detectives, together with the Special Operations Group, arrested the 32-year-old in Castlemaine after executing a search warrant at a home in the town.
"The investigation relates to the alleged possession of substances and items to assist in the manufacture of explosives," police said in a statement.
"Immediate neighbours of the home being searched have been asked to leave their homes while the Bomb Response Unit and investigators process the scene."
No further details were immediately available.