A civil court case is getting under way in the Netherlands, brought by Nigerian Ogoni activists against The Hague-based oil company, Royal Dutch Shell.
The firm is accused of having been complicit in the executions of nine Ogoni men during a Nigerian military crackdown in 1995.
Four of their widows are suing Shell for compensation and demanding an apology.
Shell denies any wrongdoing, saying it never colluded with Nigerian authorities or advocated any act of violence.
Ogoniland in the Niger Delta has long been blighted by environmental pollution blamed on oil production.
In the UK, Shell fought a legal action against Nigerians complaining their fishery had been affected.
In Italy, the firm ENI is accused of alleged corruption in the purchase of Nigerian oil fields.