"Nigeria has had enormous oil revenues for 50 years but the Delta area remains extremely impoverished and has very little to show for the billions of dollars that have poured in. Essentially, the revenues its oil industry has generated have all been stolen by the country's elite.

"The Delta area is a vast network of swamps, heavily covered with mangroves and with thick oil slicks all over the place from leaking rusty pipes. Next to these, you often see children playing barefoot in the sludge.

"There are virtually no schools or colleges. Historically, the villages subsisted on fishing which has been seriously disrupted by the arrival of the oil companies. It's extremely poor - in the slums of Port Harcourt it's rare to find a building with its roof intact.

"Against this you see the oil plants making millions of dollars every year. The big international companies argue that local people do benefit from their presence. They say that they employ local people, offer scholarships to universities, pay for teachers, schools, and various projects to help local people.

"This is true, but the problem is that when there's money involved, it creates conflict and corruption.

"The allegations against Shell and the oil companies are that they contribute to local corruption with many of their schemes and set villagers against one another when one area receives money for a pipeline but a neighbouring one does not.

"The militias involved in the attacks on the oil stations are not Greenpeace-style activists with weapons. Even though they claim to represent the marginalised communities, it is unlikely that the villagers would be any better off if these groups got their hands on the money.

"It is further complicated by the criminal gangs, many of which work closely with the security services - particularly the Navy - to illegally tap off oil from pipelines, funnel it into barges and then take it out to sea and sell it on the black market.

"The state governor of Bayelse, the state where this all happening, was recently arrested in Britain and escaped back to Nigeria, apparently dressed as a woman. He hoped that he would enjoy diplomatic immunity, but he was impeached and he is now awaiting trial.

"President Olusegun Obasanjo is also trying to increase his control over the area and rule out the wilder bandit groups who cut into the oil income.

"The President is backed by the UK and America for his anti-corruption drive. Under the constitution he must step down at the end of his second term but he doesn't seem to want to and is trying to amend the rules.

"Corrupt local officials are very unhappy about this. They were hoping that they would just have to sit it out for another year, the crackdown would be over and then it would be back to business as usual.

"The warlords and the militarised gangs are hitting back. They want to make the area ungovernable. The gangs themselves have split up, with the more radicalised extremists taking part in these latest attacks.