The National Investigation Agency (NIA) arrested Congress leader Sayem Chowdhury, popularly known as Babu, on Wednesday night, in connection with the attack on judicial officers during the special intensive revision (SIR) of electoral rolls at Mothabari in Malda on April 1.

Chowdhury, who had contested the recent Assembly elections as a Congress candidate from Mothabari, was previously summoned and questioned by the NIA in the case.

On April 1, seven judicial officers deputed to oversee the SIR process at the Mothabari BDO office under the directions of the Supreme Court were held hostage by a large mob for nearly 10 hours.

According to the investigators, after the officers were rescued through a joint operation by police and paramilitary personnel, their convoy came under attack while they were being escorted to Malda town. A woman judicial officer reportedly had a narrow escape from serious injury during the violence.

The Supreme Court subsequently ordered an NIA investigation into the incident. With Chowdhury's arrest, the total number of persons arrested in the case has risen to 68.

Isha Khan Choudhury, the Congress MP of Malda Dakshin and the party's district president, questioned the arrest.

“Sayem Chowdhury cooperated with the NIA whenever he was summoned. He clearly stated that he was not present at the spot during the incident and had attended all previous interrogations. Surprisingly, he has now been arrested. Several Trinamool Congress leaders were allegedly involved in the incident, but no visible action has been taken against them so far. We will provide all legal assistance to our party leader,” he said.

Khagen Murmu, the BJP MP of Malda Uttar, defended the investigation and urged that the probe be allowed to proceed independently.

“What happened in Mothabari on April 1 was so serious that even the Supreme Court took cognisance of the matter. The NIA is the country's premier investigative agency and should be allowed to conduct its investigation without political interference,” Murmu said.

NIA officers have not yet issued any detailed statement regarding the specific charges against Chowdhury. Investigations are in progress, said sources.