Umaru Yar’Adua, Nigeria’s president, offered an amnesty to militants in the Niger Delta on Friday as part of his strategy for ending attacks on Africa’s biggest oil industry. The offer follows the launch of a major military offensive in mid-May that has increased the pressure on armed groups.

Several faction leaders requested a meeting with the president after he announced the proposal on June 25, raising hopes that a five-week campaign of retaliatory attacks on pipelines may soon end. The attacks on facilities belonging to Chevron and Royal Dutch Shell have underscored the majors’ vulnerability to sabotage carried out deep in the delta’s swamps.