Nigeria's main militant group in the oil-producing Niger Delta says it plans more attacks on the military in a renewed onslaught on Africa's largest oil industry. Gilbert da Costa has more for VOA in this report from Abuja.

A statement from the Movement for the Emancipation of the Niger Delta, or MEND, warned that army checkpoints and armored personnel carriers in the Niger Delta will be attacked with explosive devices and cautioned civilians to avoid these targets.

The warning is bound to increase tensions in the Niger Delta days after militants invaded Port Harcourt, the main oil industry center, and killed 13 people.

Port Harcourt resident Tony Tamuno says the threat has raised fears of more turmoil in the sprawling oil city.

"Indeed everybody, the people are already apprehensive that they might be going back to the events of the middle of 2007, when there were violent clashes between cult groups and then militants attacking oil installations and military formations," said Tamuno. "People are apprehensive. They are bound to be apprehensive because militants ushered in the New Year with violence. People are now saying, is this what we are going to see in 2008? So, they are very, very apprehensive, and there is this fear among the people."

MEND also praised the New Year's Day attack in Port Harcourt and renewed its appeal to fractious armed movements active in the Niger Delta to rally against what it called a common enemy.

MEND claims it is working to improve the lives of delta residents, whom they say see little benefits from the oil extracted from their region.

Nigeria, the world's 12th largest oil producer, exports about 2.5 million barrels of oil daily. But instability and violence in the Niger Delta have cut the nation's output by more than 20 percent in the past two years, and have added to the upward pressure on global oil prices.

President Umaru YarAdua recently met his security chiefs to find a way to reduce the violence. The Nigerian military has bombarded rebel strongholds in recent days.