Police probing a claim by a man here of an alleged plot to kill Prime Minister Narendra Modi today said the National Security Act (NSA) would be slapped on him after investigations suggested there was indeed such a plan to create communal tension. City Police Commissioner K Periaiah signed the order to detain Mohammed Rafiq, arrested last month over the claim, under the NSA and the orders would be served on him tomorrow, police said. The decision to invoke the NSA was taken after a detailed inquiry and searches in the house of Rafiq, a convict in the 1998 bomb blast case who had completed his jail term. During the investigations, it had been found that there was a plot to create communal tension by targeting Modi, police said. 53-year old Rafiq was arrested on April 23 and remanded to judicial custody after a recorded telephonic conversation went viral on social media in which he is purportedly heard saying he is planning to kill Modi. Police had then registered a case under section 506 (i) of IPC (criminal intimidation) after initial inquiry suggested that his plot claim might be only to scare away the transport contractor Prakash with whom he was speaking. Rafiq's conversation with the contractor mainly related to finances about vehicles. But suddenly he was heard saying "we have decided to eliminate (Prime Minister) Modi, as we were the ones who had planted bombs when (former deputy prime minster L K) Advani visited the city in 1998," police had said quoting the eight-minute recorded conversation. The city was rocked by a series of bomb blasts in February 1998 in which 58 people were killed and over 200 people injured. Rafiq, lodged in the Central prison here after his arrest last month, is presently admitted to the Coimbatore Medical College Hospital for some heart problem.