In the swampy parts of Bayelsa State in Nigeria, film of oil shimmers in rainbow colors for hundreds of meters around Royal Dutch Shell's Nembe creek pipeline.

Shell says the cause of this latest environmental pollution,  was an unprecedented level of oil theft targeting a pipeline pumping 150,000 barrels of oil a day to the Atlantic coast.

Nembe is one of the most important production routes for Africa's top energy producer, but it is also a frequent target for criminal gangs who tap into pipelines and steal crude for sale to world markets or local refineries.

This week Shell declared force on the Nigerian Bonny Light crude oil grade and threatened to shut down the pipeline completely after thieves struck last month.

The impact on the environment of such so-called "bunkering" practices - and on the largely subsistence fishing communities who live around the pipelines in the creeks and swamps of the Niger Delta - is devastating. Decades of oil spills from a combination of theft and poor environmental management by oil majors has ravaged this fragile wetlands environment.

 David Kosipre, a former fisherman in the region says "The way of life I knew as a child, when we used to eat fresh fish straight out of the water, is all gone," David stopped plying his trade after all the fishes died due to pollution of the rivers by oil. He now uses his fishing boat to run a ferry service. He also said the oil companies have brought about a sgortage of fish as they are now been forced to buy frozen fishes rather than the fresh ones they were used to.

He also said they fear for safety as they have experienced several arrests of fishermen by military operatives who mistake them for oil thieves, yet he labelled them ( Nigeria's military) as well as some senior politicians in the delta as the "biggest thieves of all" voicing the widely held view that some in Nigeria's military are complicit in much of the theft.

Nigerian authorities reacted angrily to Shell's suggestion this week that current levels of oil theft were worse than ever, accusing the company of failing to plug pre-existing leaks.

Lieutenant Colonel Onyema Nwachukwu, a spokesman for Nigerian forces in the delta, says enforcement successes since the launch of a campaign against oil thieves last year have cut bunkering.

"There is no surge in oil theft in the Niger Delta, rather it is abating," he said at his office. "It was an outrageous outburst by SPDC (Shell Petroleum Development Corporation). We discovered breaches on SPDC pipelines over three months ago, and they have not gone to clamp those breaches down."

However Shell has disagreed with this position "Government security agencies have been deployed to protect that (Nembe) line," SPDC head Mutiu Sunmonu told reporters in the US. "But it will appear from what is happening recently that these measures are just not sufficient."

Meanwhile, the oil spills that blight the lives of millions in the delta show little sign of abating or being cleaned up.

"I barely feed my two children. They used to be in school, but there are no fish to sell, so I had to pull them out," another victim pf oil spillage in the Niger Delta, Douye Enegete, expressed angrily "Oil is a curse on us."