"I have just landed in Abuja to meet the president," Asari said. "All issues are open for discussion. If we reach an agreement, Operation Locust Feast will be suspended," he added, referring to the threatened offensive.

A spokeswoman for the government, which has called Asari a gangster, declined to confirm the meeting and said the president was not scheduled to meet the rebel leader yesterday. Asari said the meeting would take place yesterday morning, at the invitation of the government.

The rebel group on Monday issued a communique telling multinational companies to shut production in the world's seventh largest oil exporter and withdraw their staff ahead of an "all-out war on the Nigerian state."

Oil prices broke above $50 per barrel for the first time in history after Asari issued the communique, as dealers saw a further tightening of an already precarious global oil supply situation.

U.S. light crude surged to a record trading high at $50.47 a barrel this week and settled at an all-time peak of $49.90. It gained 10 cents to $50.00 a barrel yesterday.

"Our position has not changed since the communique. All foreign citizens should leave the delta," Asari said yesterday.

Oil multinationals have largely ignored the instruction to leave, but they have stepped up security in the vast area of mangrove swamps and creeks which produces almost all of the OPEC nation's 2.3 million barrels per day.

Nigeria's top oil producer, Royal Dutch Shell Group, said it evacuated more than 200 workers from two oilfields located near the fighting, but so far only small amounts of oil output have been affected.

Companies fear a repeat of last year's uprising by members of the Ijaw tribe, who are in majority in the delta, which forced them briefly to shut 40 percent of Nigeria's oil production.

SERIOUS THREAT? Oil executives were divided over how seriously to take the threats by Asari, whose following has grown rapidly in the poverty-stricken delta since he launched an armed uprising against the government last year.

"Frankly I don't take his threats seriously at all," said a senior executive at a multinational oil company. "If he attempts to harm any expatriate, he will incur the anger of the federal government and he cannot withstand that."

A security consultant at another multinational said Asari was a "serious threat to oil operations in the delta."

"If Operation Locust Feast does go ahead, it will impact oil operations. If Asari can galvanize feelings of oppression by the Ijaw people, it could get a lot worse," he said.

Asari is seen as a local hero by many members of the Ijaw tribe, who form a majority in the delta, but the government has described him as a gangster fighting for control of smuggling routes used by oil thieves.

Amnesty International said 500 civilians were killed in fighting around the oil city Port Harcourt in three weeks to mid-September, but government figures are far below that. The deaths have been mostly from sporadic gun battles between the rebels, who travel in speedboats, and newly deployed troops sent to crack down on them.

A recent consultant report for Shell estimated that about 1,000 people die every year because of communal and political unrest in the delta, where the majority live in abject poverty despite the oil wealth under their soil.

Asari is the latest in a long line of delta militants and his ideas are reminiscent of rebels such as Isaac Boro in the 1960s and Ken Saro-Wiwa, who was hanged by the late military dictator Sani Abacha in 1995.

Asari said membership of his loosely-knit volunteer force now numbered more than 200,000. His arsenal includes machine guns, assault rifles and rocket launchers, he added.

(Additional reporting by Dino Mahtani)