LAGOS - Amnesty International says oil giant Shell (IW 1000/1) could face increasing litigation internationally over oil spills in Nigeria, where parts of the country have been badly polluted.

Shell's Nigerian affiliate had not responded to requests for comment on Friday, though it has long argued that the vast majority of spills in the country's oil-producing Niger Delta were caused by sabotage.

The Delta region of Africa's largest crude producer is badly polluted from decades of oil spills, and those responsible have often not faced punishment.

"Large parts of the Niger Delta, home to more than 30 million people, have become a polluted wasteland due to the activities of oil companies," Amnesty said in a statement this week in response to a report from specialists at the University of Essex.

"Numerous oil spills have left local communities with little option but to drink polluted water, eat contaminated fish, farm on spoiled land, and breathe in air that reeks of oil and gas."

The report includes discussion of Shell's potential liability over Nigerian oil spills and warns it could face increasing litigation over such spills outside Africa's most populous country, citing various legal trends.

Amnesty said the report "draws attention to Shell’s precarious legal position arising from its appalling impacts in the Niger Delta and brings closer the day when the company will be held accountable."

Shell, the largest operator in the Delta, has consistently blamed most of the oil spills on thieves breaking into pipelines.

Oil theft is a major problem in Nigeria, with estimates putting the amount of revenue lost at more than $6 billion a year, a recent Nigerian industry investigation found.

However, activists argue that Shell does not do enough to prevent such incidents and effectively clean up the damage when they do occur.

A landmark report from the UN's environmental agency in August 2011 said decades of oil pollution in the Ogoniland region of the Niger Delta may require the world's biggest clean-up.

The United Nations Environment Program also called for the oil industry and the Nigerian government to contribute $1 billion to a clean-up fund.

Despite the UN report, little action has been taken to clean up the region.

Copyright Agence France-Presse, 2012