A politician of Tanzania's main opposition party Chama cha Demokrasia na Maendeleo (Chadema) was killed with machetes on Thursday night at his home.
The party has termed the murder a "political assassination" and called for urgent investigation into the killing of Godfrey Luena, who had been elected to represent Namwawala ward in central Morogoro.
Mr Luena is the second party official to be killed in less than a fortnight.
Chadema deputy secretary-general John Mnyika claimed in Dar es Salaam on Friday that prior to his death, Mr Luena had had differences with the local government and ruling party officials over an alleged land-grabbing by the latter.
Mr Mnyika told the media that Mr Luena had left his house to look into a power cut that had affected his house alone when he was attacked by unknown assailants armed with machetes.
Mr Luena's murder was confirmed by regional police commander Ulrich Matei, who said the motive was unknown and the killers were being sought.
"Following multiple incidents of torture, kidnapping and murder of our leaders, state organs should take this matter serious. There is need for abrupt measures to be taken by the police force. The tendency of claiming to be following up on the matter is a sign of incompetence," Mr Mnyika said.
On February 13, Daniel John, a Chadema official for Hananasif ward, Kinondoni in Dar es Salaam, was found dead with machete wounds at a beach where he had been dumped.
At the time of his death Mr John was in charge of the party's campaigns in Hananasif ahead of the Kinondoni parliamentary by-election held on February 17.
Chadema chairman Freeman Mbowe accused the ruling Chama Cha Mapinduzi (CCM) party of being behind the attack, saying: "The party in power wants to get everything by force." The government has rejected the claims.
"It has reached a point where we have to arm ourselves because we do not know who is going to be next, abductors are everywhere," Mr Mnyika said Friday.
In September 2017, a senior opposition lawmaker Tundu Lissu was shot several times at his home in Dodoma. He was rushed to Nairobi where he was in intensive care for several months, before being transferred to a hospital in Brussels where he continues to receive treatment.
Last week, the United States raised concern over "politically-related confrontations and violence" in Tanzania and called for "a transparent investigation to hold all perpetrators of violence accountable."
-Additional reporting by AFP