The UN Environment Programme, using money from Shell, has spent four years investigating and assessing thousands of oil spills in Ogoniland, the small oil-rich region of the Niger Delta where the company was active until forced out over pollution by Ogoni leaders including Ken Saro-Wiwa, who was hanged by the Nigerian military regime in 1995.The UN report will not say who caused the spills but will confirm that large areas of land remain polluted, drinking water wells are still highly toxic and many of the fishing creeks are unproductive.