CPI (M) leader Badal Shill who was critically injured in an attack in South Tripura's Rajnagar area died while undergoing treatment at a hospital on Saturday, police said.

The opposition CPI(M) alleged that Shill, a zilla parishad candidate in the panchayat polls, was murdered by BJP-backed goons, and called a 12-hour statewide bandh on Sunday.

SP of South Tripura Ashok Kumar Sinha told PTI that he was attacked by a group of people, who are yet to be identified, on Friday evening.

"Police visited the spot immediately after coming to know about the incident. The victim was not in a condition to tell the police anything. However, we lodged a suo motu case. An investigation is underway," he said.

Shill was attacked by a group of men with a 'dao' or machete, sticks and other weapons at Rajnagar market, his family alleged.

AIG (Law and Order) Ananta Das said Shill died while undergoing treatment at the state-run GB Pant Hospital in Agartala.

"His post-mortem examination has been completed and the body will be handed over to his family," he said.

Shill had on July 11 filed nomination papers for the panchayat elections.

CPI(M) state secretary Jitendra Chaudhury, who is also the leader of the opposition in the assembly, said Shill had received severe head injuries in the attack.

"This is not the death of Badal Shill, it is the murder of democracy by the BJP. I appeal to the people to protest this brutal murder and save the democracy," he said.

Left Front convenor Narayan Kar said the statewide bandh would begin at 6 am, and continue till 6 pm.

The ruling BJP could not be reached for a comment despite repeated attempts.

Panchayat elections will be held in the state on August 8, and the votes will be counted on August 10.