Police have arrested the younger brother of the suspected who was arrested for leaving a bag of 13 hand grenades near a school in Dikhena, Baduraliya.
Police have also found 900 grams of gun powder in the possession of the 31-year-old suspect. He is a resident of Hadigalla, Galthungala.
The suspect who was arrested initially, known as Hapuarachchige Pavitra Madusanka, is currently in the custody of the Colombo Crimes Division.
Media reported that the suspect had close links with a politician, however, so far no further information has been revealed.