( CNN ) -- An Amnesty International report issued Wednesday blasts Shell Oil Co. for its handling of the hundreds of oil spills that occur each year in Nigeria and accuses the company of `` serious deficiencies and abuses '' that render `` wholly unreliable '' its claims about how much oil is spilled and how often . The 80-page report , titled `` Bad Information -- Oil Spills in the Niger Delta , '' cites corrosion , poor maintenance , equipment failure , sabotage and oil theft as causes of oil spills . But it challenges the company 's assertion that the vast majority of the spills are caused by sabotage and theft . `` There is no legitimate basis for this claim , '' the report says . `` It relies on the outcome of an oil spill investigation process -- commonly known as the Joint Investigation Visit or JIV process -- in which the companies themselves are the primary investigators . '' Reliable data about the spills is critical to limiting the harm they can cause to the environment , livelihoods and human health , the report says . Determining their cause is critical because communities affected by spills blamed on sabotage or theft get no compensation in Nigeria , which is itself a flaw , the report says . `` Oil companies should be held responsible for a spill that is due to sabotage or theft if the operator has failed to take sufficient measures to prevent tampering with its infrastructure , '' it says . In response , Shell -- in a statement sent to CNN by spokesman Ross Whittam -- said : `` The Shell Petroleum Development Company of Nigeria Ltd ( SPDC ) firmly rejects unsubstantiated assertions that they have exaggerated the impact of crude oil theft and sabotage to distract attention from operational performance . `` We seek to bring greater transparency and independent oversight to the issue of oil spills , and will continue to find ways to enhance this . These efforts include publishing spill data online since January 2011 and working with Bureau Veritas , an independent third party , to find ways to improve the immediate response to a spill . '' The Amnesty report acknowledges improvements since 2011 , but says `` serious flaws remain '' in the company 's oil spill investigation process . `` These include weaknesses in the underlying evidence used to attribute spills to sabotage and the fact that the JIV reports are filled out by Shell after the joint investigation process -- not as part of the joint investigation process . There is , consequently , a lack of transparency and oversight in terms of what is recorded on the new JIV reports . '' But Shell said in its statement that SPDC can not control the joint investigation process , since it involves representatives of regulatory bodies , the Ministry of Environment , the Nigerian Police Force , the state government and affected communities . The company cited a recent report from Britain 's Chatham House that said an average of 100,000 barrels of oil were stolen each day in the first quarter of this year . `` Coordinated action from the industry , government , security forces , civil society and others is needed to end this criminality , which remains the main cause of oil pollution in the Delta today , '' it said . `` SPDC regrets that some NGOs continue to take a campaigning approach rather than focusing on on-the-ground solutions that bring societal benefits . '' Audrey Gaughran , director of global issues for Amnesty in London , rejected the company 's characterization of the report 's claims as `` unsubstantiated . '' `` The assertions are very well substantiated in the report , '' she said in a telephone interview . `` We 've taken the process down step by step , with expert advice , and provided individual cases , and all of this was provided to Shell beforehand to seek responses , and we got no responses to anything . '' She also disputed the company 's description of Bureau Veritas as independent . `` Bureau Veritas is hired by Shell , '' she said . And she said the Chatham House report is irrelevant . `` Yes , it documents significant theft , '' which is a serious issue , she said . But , she added , `` Theft is not oil spills . Proving there 's loads of theft does n't prove there 's lots of oil spills due to the theft . ''
Amnesty International cites `` serious deficiencies and abuses '' It challenges Shell 's assertion that the vast majority of spills are caused by sabotage and theft . The report says there is no evidence to support this claim, but it does not say what kind of proof they have.