Mujahid Dokubo Asari said on Tuesday the president had asked him to attend a meeting in Abuja on Wednesday, although a presidential spokeswoman said she was not aware any meeting was planned.

Asari's Niger Delta People's Volunteer Force (NDPVF) is accused by the government of trafficking oil in the Niger Delta.

It has threatened war against the government and has told foreign oil multinationals to leave the delta region, the centre of the country's substantial crude oil production.

The NDPVF says it fights for the interests of ethnic Ijaw people of the delta region, which it says have suffered neglect and deprivation despite being the source of Nigeria's oil wealth.

The multi-million dollar trade has done little to benefit the delta's impoverished people.

Declaration

On Monday, the group said it would launch an "all-out war against Nigeria" from 1 October, according to Rivers State spokesman Emmanuel Okah.

In its statement, the group also advised oil companies to leave the delta, which pumps all of Nigeria's production of 2.3 million barrels per day.

Separatist leader Asari (C) says
he will meet the president in Abuja

It also accused Royal Dutch/Shell group, Nigeria's largest oil producer, and Italy's Agip of "collaboration with the Nigerian state in acts of genocide" against the Ijaw.

Shell in Nigeria said on Tuesday that because of the unrest, it had shut a major flowstation producing some 28,000 bpd of crude.

Asari said on Tuesday he did not intend to destroy oil installations in the Niger Delta but insisted on his demand that all foreigners should leave the area.

Oil producer

Nigeria is Africa's largest oil producer and the fifth biggest in the Organisation for Petroleum Exporting Countries (OPEC).

The country derives more than 95% of its foreign exchange earnings from oil.

Unrest in the Niger Delta has helped push world oil prices to record highs, with the cost per barrel bursting through the $50 mark on Tuesday.

The United States in particular counts on Nigeria as one of its main sources of the light, low-sulphur crude which is most suitable for refining into petrol.