Another Nigerian flowstation operated by US oil giant Chevron was shut down on Friday, a company spokeswoman told Xinhua, amid dangerous tension in the country's oil delta over the arrest of a militia leader.

"We have closed the Robertkiri flowstation as a precautionary measure," Edith Azinge said. "We are monitoring the situation closely."

The oil facility is close to the Idama flowstation, which was occupied on Thursday by over 100 armed militants of the illegal Niger Delta People's Volunteer Force (NDPVF). The closures have led to the loss of 26,000 barrels of oil production per day in OPEC Nigeria.

Royal Dutch Shell, which accounts for about half of Nigeria's oil production, however, said its oil production had not been affected and reopened their offices in the southern oil city of Port Harcourt on Friday.

The tension is the result of the arrest of NDPVF top leader Alhaji Mujahid Dokubo Asari early this week as the group threatened to attack all oil installations if Asari would not be released soon.

The Nigerian police had said Asari was arrested over "seditious and treasonable" comments in a recent exclusive interview with a Nigerian newspaper.

"Nigeria is an evil entity. It has nothing to stand on and I will continue to fight and try to see that Nigeria dissolves and disintegrates," Asari said then.

On Thursday, Asari appeared briefly before a high court in the capital Abuja, which ordered he remain detained for two weeks before formal charges of treason are brought. "I have been held for 48 hours ... you cannot detain me beyond 48 hours," he shouted, challenging the government to put him on trial without further delay.

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.

Following his arrest, unrest seemed to return to the Niger Delta, where the majority of Nigeria's oil is produced.

Nigeria has deployed two naval warships, fighter jets and two helicopters to the region and military operations there have been put on high alert to forestall threat to key oil production and export faculties, Nigeria's ThisDay newspaper quoted reliable security sources as saying on Friday.

Nigeria is the largest oil producer in Africa and the eighth largest oil exporter in the world with the output of crude of over 2.5 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.

Source: Xinhua