Rab sources said Zahidul Islam Zahid, 35, former ward commissioner of Kushtia municipality, had links with an underground outfit. He sustained injuries in the chest and legs as he tried to flee during his arrest, they added.

He was taken to Kushtia General Hospital where he died at about 11:45pm.

Zahid's family claimed that he died due to inhumane torture in Rab custody. Rab officials denied the allegation.

Rab arrested Zahid during a raid in Badhpara-Charmilpara area of the town at 11:00am on Monday. The law enforcers later interrogated him at their camp.

After his arrest, over a thousand people demonstrated in the town demanding immediate release of the ex-ward commissioner. They also submitted a memorandum to the deputy commissioner in this regard.

RAB said Zahid was handed over to Kushtia Sadar police in the evening. Police later produced him before a court, which sent him to jail.

Police said Zahid was an accused in seven cases including three for murder. A court had also sentenced him to 10 years' imprisonment in one of the cases.

Meanwhile, Kushtia district administration has formed a one-member committee to investigate the incident.

"Necessary steps will be taken after submission of the probe report," Deputy Commissioner Talukder Shamsur Rahman told journalists.