Rival gangs involved in stealing an estimated 100,000 barrels of crude oil a day from pipelines and wellheads have stepped up attacks in the eastern Niger delta in the state of Rivers.
"This level of violence represents a serious threat to the region," said George Ngwa, an Amnesty International press officer for African Affairs, on Thursday.
Security forces have already begun 24-hour patrols in and around the state capital and oil hub Port Harcourt after a surge of fighting in August. The gangs, which sell the oil to buy weapons, are often backed by local political and ethnic leaders.
Many gangs were originally armed
to fight turf battles during polls
"We sent an open letter to the Rivers state government on the 15 [September], after our sources on the ground reported 500 dead in the last few weeks," Ngwa said by phone from London.
State authorities were not immediately available for comment. Local officials have confirmed several incidents through August, but the combined death toll comes nowhere near the figure cited by Amnesty.
The chronic ethno-political conflict in the delta has threatened oil operations in the world's seventh largest oil exporter of 2.5 million barrels per day.
Many of the gangs were originally armed to fight turf battles on behalf of politicians during the 2003 elections, and recruit their fighters from young disillusioned men in the impoverished delta.
"This level of violence represents a serious threat to the region"
press officer for African Affairs,
Rivers state Governor Peter Odili earlier in September ordered top members of his government to leave office in what was described as a purge of public figures linked to criminal gangs.
Although the violence in the eastern delta has not halted exports, ethnic clashes in the western delta in 2003 forced oil multinationals to temporarily shut 40% of output.
At least 11,000 people have been killed in sectarian fighting since Nigeria emerged from 15 years of military rule in 1999.