In the oil-rich Niger Delta, the struggle among local leaders for oil revenue and government funds has fueled violent clashes between rival armed groups, Human Rights Watch said in a new report. An escalation in violence last year killed dozens of innocent people and disrupted oil production, pushing global crude futures over a record $50 a barrel. The 22-page report, "Rivers and Blood: Guns, Oil and Power in Nigeria's Rivers State," based on a December fact-finding mission to the region, documents fighting between armed groups in the southeastern oil-producing state that escalated in late 2003 and continued throughout 2004. The clashes resulted in the indiscriminate killing of local people, displaced tens of thousands of villagers from their homes, and forced the oil industry to evacuate staff and scale back its production. On October 1, the federal government brokered a peace agreement between the two main rival armed groups. The federal and state governments then granted an amnesty to the fighters. While commending the government's effort to end the conflict, Human Rights Watch said that the perpetrators of grave human rights abuses must not be given immunity from prosecution.