Internal Shell Nigeria documents show that the company was advised by its own staff in 2002 to immediately replace a 30 year old pipeline passing through impoverished delta communities because it continually leaked and was a major risk.
The 24 in. trans-Niger pipeline in question then burst twice within a few days in November 2008, spilling thousands of barrels of oil.
Oil firm Royal Dutch Shell was told a pipeline had reached the end of its life years before it spilled up to 500 000 barrels of oil, according to court documents seen by the BBC.
Other Shell documents, filed with the London high court and obtained by Amnesty International, suggest that the company underplayed the magnitude of the two spills that occurred near Bodo in Ogoniland.
Shell investigation reports for the two spills claim that only about 4000 barrels of oil were spilt in total. However, an independent assessment published by US firm Accufacts Inc. calculated that the amount spilt exceeded 100 000 barrels.
Shell Petroleum Development Company (SPDC) is being sued by 15 000 villagers living near Bodo.
Edited from various sources by Elizabeth Corner
Sources: The Guardian, BBC