Patrick Naagbanton, the Ogoni director of the Niger Delta Project for Environment, Human Rights and Development, says: "There is the same environmental pollution, degradation of the environment, the same harassment of our people by the military, and the oil communities continue to use armed guards."

Inspired by the Ogoni uprising, other ethnic groups in a region of 12 million people have stood up to fight the oil industry and the Nigerian government. The Illaje have protested against US giant Chevron, leading to protesters being killed and tortured. The Ijaw, one of the largest delta groups, mobilised in the late 1990s, demanding an end to oil production on their land. The military was called in and more than 200 people were killed, tortured and raped, according to Human Rights Watch.

By 2000, another lethal ingredient had been added to the tinderbox of the delta. "Oil bunkering" - the siphoning of oil from the myriad pipelines, to be sold on the black market - was now accounting for 10% or more of Nigeria's oil production. And much of this was funding the purchase of arms.

When Alhaji Dobuko Asari, leader of the Niger Delta People's Volunteer Force, threatened all-out war in the delta in September 2004, the world oil price rocketed to $50 (£28) a barrel for the first time. A peace deal was signed, but Asari was arrested in Port Harcourt a year later and charged with five counts of treason last month. He could face the death penalty if convicted. The date of the trial has been set for November 10 - a day activists see as being beyond coincidence.

Meanwhile, the oil industry has been moving, where possible, offshore in the Gulf of Guinea. Nigeria's offshore reserves account for about 25% of its total.

In 2003, a leaked report from a Shell consultant argued that the company had become "an integral part of the Nigeria Delta conflict system". But Shell maintains that the situation is improving. Alan Detheridge, vice-president of external affairs for Shell Exploration and Production, says: "Controllable oil spills ... have reduced very substantially, from 11,500 barrels in 1995 to 290 barrels in 2004."

Meanwhile, the delta is on the verge of another new development. Nigeria's vast gas reserves, which have traditionally been flared, are increasingly being liquefied for export, with the UK keen to secure resources as North Sea reserves dwindle.

Neo-conservative thinktanks that led the Bush administration to war in Iraq now talk of the Gulf of Guinea as the "next Gulf", an area of strategic interest, to be protected by the military might of America and her allies, including the British.

Ledum Mitee, president of the Movement for the Survival of Ogoni People, the organisation Saro-Wiwa once led, fears for the future. "The American policies that have had a doubtful effect in the Middle East have focused their attention around the Gulf of Guinea," he says. "It is not people-centred. It is just barrel-centred. It could become so bad that in five years it will be very difficult to get a barrel of oil without [costing] a life."

· Andy Rowell is, with James Marriott and Lorne Stockman, joint author of The Next Gulf - London, Washington and Oil Conflict in Nigeria, published this week by Constable and Robinson (£8.99).