"I am aware that soldiers have been sent in. But I don't have the details yet," Colonel Onwuamaegbu Chukwuemeka told AFP.

The soldiers were ordered in on Tuesday following four days of violent clashes between naval personnel and armed militant youths from the Ijaw ethnic group in southern Nigeria's oil-rich Niger delta region, he added.

Ten people, including two soldiers and a naval officer, have been killed in the fighting, army authorities told AFP.

The youths have razed two fishing villages belonging to the rival ethnic Itsekiri community in the area, they said.

Trouble started last Thursday between Ijaw youths and naval personnel patrolling the waterways.

The violence has hit oil production, putting pressure on supplies from Africa's biggest exporter as worries over a US-led attack on Iraq disturbed world prices.

Anglo-Dutch oil group Shell, Nigeria's major oil operator, told AFP Wednesday five oil flow stations, accounting for 76,000 barrels per day (bpd) have been shut down because of the unrest.

Two flow stations, accounting for 30,000 bpd were closed down on Monday while three more with a combined production capacity of 46,000 bpd were shut on Tuesday, the company said.

US oil giant ChevronTexaco, which also operates in the area, has said in a statement that two contract workers were hit by stray bullets during the fighting.

It said one of them died on Tuesday while the other was in critical condition in hospital.

The company did not say if the crisis has affected its operations.

Airport officials told AFP flights have been suspended to the troubled area because of the violence.

"We have cancelled all flights to and from Warri and its environs because of the crisis. We shall resume operations when things are calm," they said.

The Warri crisis is the latest in a series of violent incidents that have rocked Africa's most populous country less than six weeks before the start of the country's first national polls since the return to civilian rule four years ago.

Dozens of people have been killed in riots and assassinated in recent weeks.

More than 10,000 people have died in mob violence since Nigeria's 1999 return to civilian rule, and the Nigerian Red Cross says it is caring for more than 57,000 who have been driven from their homes.

On Monday a spokesman for the northwestern state of Kebbi told AFP by telephone that 200 houses had been burnt down over the weekend in clashes between opposition and ruling party supporters.

President Olusegun Obasanjo, who is seeking a second tern in next month's presidential election, was due Wednesday to hold talks with political parties and other stakeholders on how to stem political violence ahead of the elections.

WAR.WIRE