New Delhi: The National Investigation Agency (NIA) on Saturday carried out extensive search operations at 19 locations across Keralam, Karnataka, and Tamil Nadu in connection with its ongoing probe into the seizure of illegal explosives from Keralam's Malappuram district.An official said the searches are part of a coordinated effort to trace the origin, supply chain, and possible network involved in the storage and movement of the explosives.Read more: NIA arrests 15 in SIR-linked road blockades in Bengal, judges' detention caseThe case pertains to the recovery of a significant quantity of unauthorised explosive materials from Malappuram, raising concerns over potential misuse and security threats.The NIA took over this case earlier this year from Keralam Police, considering the gravity of the case.The multi-state raids are being conducted simultaneously since early Saturday at premises linked to suspects believed to be associated with the procurement and distribution of the seized materials.Investigators are focusing on uncovering links between individuals and any organised groups that may be operating across state boundaries.Preliminary inputs suggest that the explosives may have been sourced and transported through a network spanning southern states, prompting the NIA to widen the scope of its investigation.Officials are also examining whether the materials were intended for unlawful activities or illicit trade.Read more: Delhi Red Fort blast: NIA chargesheet reveals abuse of AI platform for 'terror engineering'Search teams have been deployed at multiple residential and commercial locations, where they are scrutinising documents, digital devices, and other evidence that could shed light on the case.The NIA, India's premier counter-terrorism investigative agency, has intensified its efforts in recent months to curb illegal arms and explosives networks, particularly those with inter-state linkages.