Gopalganj Sadar police OC Jakir Hossain Molla said the deceased Lakku Molla, 63, was a retired army man and his brother Makku Molla was the incumbent Union Parishad member.
Makku has a long-lasting power struggle with former UP member Khokon Molla over local control.
Around 7am on Tuesday, members of the Khokan group pounced on Lakku who was alone on the road beside his house and hacked him with sharp weapons, the OC said.
Makku, who was also injured when he tried to save his brother, said Lakku died after he was taken to Gopalganj Sadar Hospital.
He also accused Khokon of masterminding the attack although he could not name any of the assailants, the police official said.
Jakir Hossain said police has detained four women from the area for questioning.
He added that supporters of Makku and Khokon have clashed before as well.
On November 2014, henchmen of Makku hacked and injured Khokon’s brother Farid Molla. Both Makku and Khokon have a number of cases against them over these violent incidents.