LAGOS, Sept. 22(Xinhuanet)-- Over 100 armed militants on Thursday attacked and took over a Nigerian oil flowstation operated by US oil giant Chevron, a company spokesman told Xinhua,as tension in African top crude producer's oil delta built up overthe arrest of their leader.

"A large crowd of people, some of them armed, came to the flowstation this morning," Edith Azinge said, noting that there was no injury during the occupation of Idama flowstation in the oil-rich Niger Delta by militants of illegal Niger Delta People's Volunteer Force(NDPVF).

"We have shut the flowstation in the interest of our oil workers... evacuating non-essential personnel from nearby facilities as a precautionary measure," she said.

The Idama flowstation is only producing about 8,000 barrels of crude per day but the militants had threatened to attack all oil installations if their top leader Alhaji Mujahid Dokubo Asari would not be released soon.

"We will continue to monitor the situation very closely and will make decisions as circumstances dictate," Azinge said.

Asari was arrested in Port Harcourt, the hub of Nigeria's oil operations in the southern Niger Delta, where the majority of the country's oil is produced, and immediately flown to the capital Abuja on Tuesday.

Sporadic gunfire erupted in the oil city that night as his followers took to the streets to demand the release, forcing the closure of banks, schools and shops there the following day. His followers meanwhile threatened to disrupt oil production in the Niger Delta.

In a swift reaction, Royal Dutch Shell, which accounts for about half of Nigeria's oil production, advised its staff in the delta to be on the alert and those in Port Harcourt to stay at home.

Shell spokesman Bisi Ojediran, however, said its oil productionhas not been affected."Everything is all right. We will open our office tomorrow(Friday)," he said.

Last year, Asari threatened to launch an overall war against foreign oil companies which helped increase the price of crude to 50 US dollars a barrel. But President Olusegun Obasanjo later invited him for peace talks in Abuja, where they reached a ceasefire agreement. Since then, he moved to Port Harcourt and surrendered thousands of assault rifles and machine guns.

On Thursday, Asari appeared briefly before a high court in Abuja, which ordered he remain detained for two weeks before formal charges of treason are brought.

The Nigerian police had said Asari was arrested over"seditiousand treasonable" comments. In a recent exclusive interview given to the Daily Independent, a leading daily newspaper in Nigeria, Asari said:"Nigeria is an evil entity. It has nothing to stand onand I will continue to fight and try to see that Nigeria dissolvesand disintegrates."

Nigeria is the largest oil producer in Africa and the eighth largest oil exporter in the world with the output of crude of over2.5 million barrels per day.

The people of Niger Delta, however, still live in abject poverty, accusing foreign oil companies of environmental degradation and not doing anything to develop the impoverished area. Seizures of oil facilities, kidnapping of oil workers and threat of violence there are common. Enditem