Western-based oil company Royal Dutch Shell says it hopes to quickly repair and resume production in an oil pipeline in Nigeria's Niger Delta region that was attacked by militants Friday. Gilbert da Costa reports the attack has raised concerns of more violence against Nigeria's oil industry.

Nigeria map hightlighting Delta eng 190

Pressure groups in Nigeria's Niger Delta warn Friday's attack could ignite another round of violence in the volatile region. The Movement for the Emancipation of the Niger Delta, the main militant group that claimed responsibility for the blast, says it plans more attacks.

Several issues are driving tensions in the region.

Henry Okah, a leader of The Movement for the Emancipation of the Niger Delta, or MEND, is being tried in a secret court for treason.

Militants are also blaming the military for the destruction of some 20 houses in the Opuama community of Delta State, the alleged consequence of a failed attack on a Chevron oil facility in the area.

Meanwhile, Ijaws, the dominant ethnic group in the delta, are locked in a dispute with the state governor over the election of local officials.

Udengs Eradiri of the Ijaw Youth Council, a leading pressure group in the delta, says the military is being used to settle political scores in the delta's creeks. "The Joint Task Force that has been deployed in the Niger Delta to quell the situation in the region; what government officials or politicians do these days is that when you are agitating for your rights, they will send them [soldiers] and say you are a militant. You [governor] sent JTF [Joint Task Force] to burn down our villagers. Opuama was burnt, people killed. Today there is a crisis in the area, the Ijaws are mobilizing to go there and see how they can help their brothers. We are saying we want to be included in the political dynamics of Delta state," he said.

Militant attacks have already cut one quarter of the normal two-point-five million barrels per day oil output in Africa's largest producer of crude.

Militants say they are fighting for control of the region's oil wealth, but their fight is intertwined with communal and ethnic rivalries in the delta, where kidnapping for ransom, extortion and oil theft are widespread.

The main militant group declared a truce after the inauguration of President Umaru Yar'Adua in May, who promised to resolve the crisis. MEND announced in September it would resume attacks following Okah's arrest and extradition from Angola.