An agreed ceasefire in the Nigeria’s oil-producing Niger Delta is in danger of being derailed by anger at the military over the death of an elderly local leader.

The Niger Delta Avengers group, whose attacks on oil pipelines in the southern region crippled crude output earlier this year and pushed Africa’s biggest economy into recession, said in August it agreed to a ceasefire.

The government has held out the prospect of holding talks on the grievances of people in the Delta with militant groups which maintain a truce.

But the death last week of Chief Thomas Ekpemupolo, the father of a fugitive former militant leader, could rekindle hostilities.

The octogenarian fell while fleeing an army raid on his home town in May and injured his leg, which had to be amputated two months later, said a spokesman for his son, former militant leader Government Ekpemupolo, known as Tompolo.

Militants launched a wave of attacks at the start of the year to demand a greater share of oil revenues for the swampy region, which produces most of Nigeria’s crude but whose residents are mired in poverty.

Security sources say Tompolo has links to those responsible for the attacks, which began shortly after corruption charges were brought against him. He has denied any involvement.

“In a nutshell, (the) government caused the death of my father,” said Frank Ekpemupolo, another son, raising his voice above the traditional music played through giant speakers at a gathering of 400 mourners at his father’s compound in Warri, the largest city in Delta state.

Mourners including community chiefs, politicians and villagers accused troops of harassing people in the fishing communities dotted along the region’s waterways.

An Avengers spokesman told Reuters the military was “harassing poor people of the Niger Delta”. The military denies it, saying troops are merely searching for militants and criminals.

Several new militant groups have sprung up in the last few weeks, each with its own demands, and some have vowed to launch a new wave of attacks.

Community leaders say they are concerned that the government has not contacted militants or unveiled a negotiation team, three weeks after the Avengers said they were ready for the promised talks.

“We haven’t been contacted, but we are not worried,” said the Avengers spokesman.

“They have only stopped bombing temporarily. It doesn’t mean they are tired of bombing,” he said.

An army offensive was launched in late August against militant camps and led to the deaths of five people and the arrests of 23 others.

Eric Omare, spokesman for the Ijaw Youth Council, which represents one of the region’s largest ethnic groups, said statements by President Muhammadu Buhari that militants would be treated like Boko Haram jihadists prompted fears that the offer of talks was a ruse to prepare for a military onslaught.

Tensions in Warri are concentrated along its murky brown waterways – used by fishermen, commuters and thieves stealing crude oil – where fleeting encounters with strangers can end in bloodshed.

Boats slow down and their occupants raise their arms when they encounter naval patrol boats fitted with machineguns.

Fishermen say they fear being mistaken for militants and shot. Gunmen disguised as priests killed three soldiers last month.

An official who did not want to be named said “arrangements” were being made to resume dialogue with the militants.

He said the government wanted each militant group to send representatives, rather than acting through intermediaries as in the past.