The Niger Delta Avengers, a militant group that has been attacking Nigeria's oil infrastructure since early this year, is anything but new, according to those familiar with the region.

Despite their fresh name, it was only a matter of time before the militants returned to the swamps and creeks of the delta region, the sources said.

The "boys" behind years of violence a decade ago surrendered their guns in 2009 when the government introduced an amnesty programme for militants, once described as a "bribe for peace".

Thousands stopped bombing oil pipelines to go overseas for skills training as divers, welders and boat builders using monthly stipends of 65,000 naira, which at the time was worth $400.

Then last year President Muhammadu Buhari announced he was planning to wind down the programme as well as lucrative pipeline security contracts to save money for the cash-strapped government.

"That infuriated everybody," said Silva Ofugara, chairman of the Ekpan-Uvwie community in the oil town of Warri in Delta state.

The militants had been getting something from the government, a monetary acknowledgement that they too should benefit from Nigeria's vast oil wealth.

People thought they could leave their lives as guerilla fighters behind and focus on a new future.

"A year ago nobody wanted to go back to the creeks," Ofugara told AFP alongside local leader Ufuoma "White Don" Ikaka, wearing a black leather jacket and shirt the colour of the US Stars and Stripes.

But Buhari's announcement changed their minds. For many, the amnesty money was their only income.

"This brought boys to the roundtable to prepare for the next phase."

- 'Kegs of gunpowder' -

Leading the charge are the Niger Delta Avengers, a previously unheard of group, which has claimed a series of attacks on pipelines and facilities mostly in Delta and Bayelsa states.

They have targeted facilities operated by the Nigerian National Petroleum Corporation, as well as local subsidiaries of Shell, Chevron and Eni.

In the impoverished region, the Avengers are anything but unknown.

"The only way they know how to survive is pulling a trigger," said Uche Ifukor, project manager at the Warri-based non-profit organisation AA PeaceWorks.

The militants never found jobs in Warri despite it being home to the biggest oil fields in Africa, he added.

Each militant kingpin -- or "civilian general" -- still commands legions of men from the days before the amnesty deal, Ifukor said.

The generals are effectively the "godfathers" of the oil mafias that run the creeks. Ifukor called them "kegs of gunpowder... just waiting for the wrong move".

- Anarchy returns -

The attacks have cut oil production to some 1.6 million barrels per day, well down from a budgeted 2.2 million bpd, as global prices remain low, sending Nigeria's economy into a tailspin.

In response, the army has started invading river land villages, hunting for the Avengers and the influential militant kingpin-turned-businessman Government "Tompolo" Ekpemupolo, who has been on the run since he was charged last year with corruption.

The result: a return to anarchy in the delta, shootouts between militants and soldiers -- and Ijaw civilians, the dominant ethnic group in the region, caught in the crossfire.

The villages of Okerenkoko and Kuritie in the Gbaramatu Kingdom, the region of snaking waterways stretching from Chevron's Escravos terminal on the Atlantic Ocean coast to Warri, have been abandoned.

People fear a repeat of air raids in 2009 that levelled communities in the final weeks before the government and Tompolo hammered out the amnesty deal.

"The average life in Gbaramatu Kingdom is brutish, short. I just buried my sister yesterday," said Chief Godspower Gbenekama, of the Gbaramatu Kingdom.

Floral Joel was selling wares in a houseboat on June 1. Soldiers chasing militants opened fire on the boat, shooting the 42-year-old mother of five in the heart, he added.

"My sister paid a supreme price," he said. "As it is, every Ijaw man is an Avenger. We are an endangered species."

- Muzzled hyenas? -

Not everyone in Nigeria is sympathetic to the Avengers, whose demands include self-determination for the delta region and the withdrawal of foreign oil majors.

One recent newspaper editorial depicted the militants as unleashed hyenas who had been muzzled by the amnesty and security contract cash doled out by former President Goodluck Jonathan.

Yet without peace in the Niger delta, which produces the bulk of Nigeria's oil, Buhari will struggle to source funds needed to kick-start the economy during its worst slowdown in a decade.

"The best case scenario is the Avengers agree to hold talks with the government, and some form of compromise is made whereby the government gives payments in order to stop further attacks," said Rhidoy Rashid, an analyst at London-based Energy Aspects.

"Worst case is the attacks continue, and even worse turn violent. They are more than just aggrieved locals and have access to sophisticated weaponry and funding."

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