Three people were arrested on Wednesday in connection with the recent car bomb blast in front of Kottai Eswaran Temple here, the NIA said.
The blast in the car laden with explosives on the eve of Diwali left its occupant, a terrorist who had taken oath to global terror group ISIS, dead.
Initially, a case was registered at the Ukkadam Police Station in Coimbatore on October 23 and later re-registered by the National Investigation Agency (NIA) on October 27.
Umar Faaruq (39) alias K Srinivasan of Nilgiris district, Mohammed Thoufeek (25), and Ferose Khan (28) of Coimbatore were arrested for their involvement in the October 23 explosion, an NIA spokesperson said.
"After preliminary investigations, it has emerged that the deceased accused, Jamesha Mubeen, after taking 'bayath' (oath of allegiance) to the ISIS, planned to carry out a suicidal attack and cause extensive damage to symbols and monuments of a particular religious faith and with the intention to strike terror among people," the spokesperson said.
The official said the investigations have revealed that Faaruq and Khan were part of the conspiracy meetings attended by Mubeen at Faaruq's residence at Coonor in Nilgiris district. The accused also provided support to Mubeen in the commission of the terror act.
"Thoufeek was in possession of incriminating literature and books connected to radical Islam and also had handwritten notes on preparation of explosives," the spokesperson said.