Nigeria's largest oil producer Shell was fined in 2000 for environmental damage through its exploration in the Niger Delta.
According to the UK's Times Online, Shell refused to pay and has since been targeted by Ijaw militants who have attacked the company’s workers and facilities. The fine was upheld this week by the Nigerian Federal High Court.
A statement from the Movement for the Emancipation of the Niger Delta, the armed ethnic Ijaw group claiming responsibility for the offensive, said: "We are continuing with our attacks on oil facilities and oil workers... We will act without further warning."
Following the violence, Shell has been forced to slow output from Nigeria's southern delta region where it began oil production in 1956. Shell contends that most oil spills in the region are caused by saboteurs trying to steal oil.