Shafir Ali, an engineering diploma holder, was arrested on August 6 by CISF personnel as they found in his possesssion pen drives and card readers while frisking him before letting him in for his daily duty, police said.
He was later handed over to Kancheepuram Police.
Police, who have been investigating the case, had found out that Shafir had travelled often to places like Dubai, and have been tracking his various connections.
Shafir, who was arrested under section 18 of the Atomic Energy Act, 1962, is in judicial custody and lodged at the Puzhal prison.