In pictures: Fighting for Nigeria's oil

Mujahid Dokubu-Asari used to be president of the influential Ijaw Youth Council - the ethnic group which makes up the bulk of the Delta's population.

He lives in the region's swamps and creeks and says the police only started hunting him after he accused the Rivers State governor of rigging last year's elections.

The authorities say his group has fought a bitter turf war with a rival militia, known as "The Icelanders".