How Shell 'fixes' its pollution record in the Niger Delta

Shell has always claimed the oil spills which pollute villages, farms and fisheries in Nigeria's Niger Delta are mainly due to locals sabotaging pipelines for political reasons or theft. But a painstakingly researched report yesterday alleged that, in fact, corrosion and poor maintenance by the British oil multinational were the real reason for many of the spillages.

Amnesty has dismissed Shell's investigation reports into its spills as "nothing more than dodgy dossiers" in which the findings were often "very subjective, misleading and downright false".

The human rights organisation hired an independent pipeline specialist, Accufacts, to investigate.

Using the same data employed by Shell and the regulators, Accufacts' research found "serious and systemic flaws" in the oil spill investigation process and clear examples of company executives attributing leaks to sabotage without any evidence. Corrosion was clearly evident in many cases.

Spills have meant many people living in the Niger Delta have to drink, cook and wash with polluted water, eat contaminated fish and farm from contaminated land.

But it is not only for public relations reasons that Shell might want to shift the blame for spills on to local thieves and vandals: oil companies do not have to compensate villagers for spills caused by vandalism. Shell's official Sustainability Report claimed sabotage and theft were responsible for "more than 80 per cent" of the volume of spills from its facilities in 2010. Amnesty's investigation casts serious doubt over how much those figures should be trusted.

After each spill, a "joint investigation visit" is made, in which representatives from several regulatory agencies take part. However, they are reliant on the oil companies for transport and technical expertise. Amnesty said this regime is hopelessly inadequate, with cash-starved regulators forced to trust the oil companies' own investigations.

Audrey Gaughran, director of global issues at Amnesty said: "This is a system that is wide open to abuse – and abuse happens. There is no one to challenge the oil companies and almost no way to independently verify what they say. In effect it's "trust us – we're big oil".

Undercover video of one investigation showed officials from Shell and the regulators clearly trying to subvert the evidence by persuading community members not to attribute a leak to equipment failure.

Shell denied exaggerating the impact of theft and sabotage, saying it acts transparently, publishing spill data online and working with Bureau Veritas, an independent third party, to find ways to improve the immediate response to a spill.