African heads of state and African Union and United Nations officials will sit down opposite Sudan’s president in the Nigerian capital Abuja on Thursday afternoon to try to hammer out the specifics of an agreement earlier this month by Sudan to allow the UN to put boots on the ground in wartorn Darfur.

Nigeria’s President and former AU chariman Olusegun Obasanjo, Senegal President Abdoulaye Wade, Ghana President John Kufuor and Libya President Muammar Ghaddafi will face off opposite Sudanese President Omar al-Bashir, AU officials said.

Bashir has steadfastly refused collective pressure from AU members and the international community to allow the UN to put peacekeepers into Darfur in western Sudan, claiming that the UN has colonialist designs in Sudan and comparing the UN in Sudan to the American-led presence in Iraq.

Earlier this month at a meeting in the Ethiopian capital Addis Ababa, the Sudanese government “agreed in principle” to a hybrid AU and UN force, but final agreement was left contingent on the size of the force. Sudan expressed reservations over the proposed size of 17,000 troops a 3,000 police to be deployed in Darfur.

The AU has 7,000 troops in Darfur, but critics say the under-funded force has been largely unable to stem the violence. The AU’s mandate to operate in Sudan has already been extended once and now expires finally on 31 December.

Sudan has agreed that logistical, communications and financial support officers and helicopters and armoured cars can be added to the AU’s force, but specific numbers were not agreed at the Addis meeting.

“Bashir is supposed to speak to the peace and security council because there is an important decision to be made about the concept of a hybrid force,” Sam Ibok, who heads the AU’s Darfur peace implementation committee, said. “This is a meeting to decide whether this proposal is acceptable to the government of Sudan,” he added.

Outgoing UN secretary general Kofi Annan told reporters in New York on Tuesday he was awaiting the response of the Sudanese leader to the plan to have a hybrid force in Darfur.

Annan said he expected the meeting in Abuja to help resolve outstanding issues on the size of the force, the appointment of a representative to liase with the AU and the UN, as well as the choice of a force commander.

If Sudan rejects the proposals for a joint force, a decision will still have to be taken at today’s meeting on what will happen when the mandate of the African force expires, mediators said.

Some three years of fighting in Darfur between rebel and government forces has caused the death of at least 200,000 people according to the UN, and forced another 2.5 million from their homes, some of them into neighbouring Chad.

Violence has persisted in Darfur despite a peace agreement reached in Abuja in May between Khartoum and the main faction of the rebel Sudanese Liberation Army after more than a year of difficult talks. That deal was mediated by Nigerian President Obasanjo.

Aid agencies report that a lull following the peace agreement’s signing has been followed by some of the most widespread raping, killing and looting seen in Darfur since fighting started.

The mainly black African tribes in Sudan’s western Darfur region took up arms against al-Bashir’s government in 2003, alleging they had suffered decades of oppression. The government responded with a military crackdown and has allegedly sponsored the mainly Arab Janjawid militia that is accused of committing atrocities against unarmed Darfuri civilians and in neighbouring eastern Chad.