The National Investigation Agency (NIA) has arrested a "local political leader" in an SIR-related violence case over alleged mob blockades and detention of judicial officers in Bengal's Malda district in April, officials said on Thursday.

Sayem Chowdhary alias Babu Chowdhary, a political leader from Mothbari (Malda), was taken into custody by an NIA team after he was questioned at the agency's branch office in Kolkata, an NIA statement said.

A total of 30 persons have been arrested by NIA so far in this case.

The central agency is investigating over a dozen cases of mob protests and illegal detention of judicial officers during the Special Intensive Revision (SIR) exercise in Malda district ahead of the West Bengal Assembly polls.

NIA investigations revealed that Chowdhary was a key accused in illegal detention of judicial officers at BDO Office Block-II on April 1, 2026.

He was allegedly part of the mob that caused "disruption of law and order", and attacked police personnel engaged in official duty, the statement said, adding that nine police personnel were injured in the attacks.

The NIA investigation has found that the accused had delivered a speech in front of the BDO office a day before the incident to instigate people to engage in violent protests, the agency said.

Chowdhary had allegedly conspired with other co-accused and participated actively in unlawful assemblies that resorted to violence, intimidation, and obstruction during the SIR exercise, it added.

The NIA is trying to identify and track all persons involved in various cases of pre-poll violence in West Bengal as part of its probe into the larger conspiracy behind these incidents, the statement said.

The agency initiated investigation into these cases on directions of the Supreme Court, which had taken suo moto cognisance of April's violence in Malda.