Leaders of an ethnic uprising in Nigeria's oil-rich Niger River delta said they have stopped fighting government forces, ending a two-week siege that caused a nearly 40 percent drop in oil production in the West African country.

Members of the ethnic Ijaw group, who have been fighting government forces for two weeks, said they decided to put down their weapons after meeting Tuesday with the government of Delta state.

Starting March 13, the Ijaws attacked oil facilities, clashed with members of the rival Itsekeri group, and fought with the Nigerian military as they pressed their demands for greater political representation. The skirmishes left at least 13 dead during the past two weeks.

The government of President Olusegun Obasanjo dispatched hundreds of troops to quell the violence.

Wednesday, leaders of the uprising said they had stopped fighting, but warned they would resume their attacks if the government does not meet their demands. These include the re-drawing of electoral districts before general elections, which are scheduled for April 19.

The Ijaws, who consider themselves the majority in the region, say current political boundaries were laid to the Ijaws' disadvantage. They accuse rival Itsekeris, who hold more seats in the local council, of trying to monopolize political power.

The violence prompted three foreign oil companies to halt operations in the Niger River delta. The shutdowns cut daily oil production by a third in Nigeria, the world's sixth largest producer of oil.