General Paulo Lukamba Gato, the new leader of the Unita movement, arrived in the Angolan capital Luanda on Tuesday in preparation for the signing.

Speaking on state radio soon after he arrived, Mr Gato said that Angola would now enjoy what he called a definitive peace.

However, a reminder of the country's continuing instability came on Monday when seven people were reportedly killed in an ambush in the central town of Huambo.

A local official blamed the attack on Unita bandits, Catholic radio station Radio Ecclesia reports.

Integration

The amnesty, approved unanimously, covers "all civilians and soldiers, Angolan or foreign, who committed crimes against the security of the Angolan state" as well as "any person imprisoned during the war" and "deserters" from the Angolan army.

Another key aspect of the peace deal is the integration of some 50,000 former Unita fighters into the government army.

General Gato is accepted as Unita's new leader

The agreement comes just five weeks after the death of Unita's founding president, Jonas Savimbi.

He was killed by government troops and so too - it is widely believed - was his vice-president, Antonio Dembo.

General Gato, as Unita's Secretary General, is now the most senior political figure in the movement.

The presence in Luanda of Mr Gato - together with the commander in chief of Unita's armed forces, General Abreu Kamorteiro - has helped to boost confidence that the signing of the ceasefire will go ahead as planned.

Sanctions

However United Nations sanctions still remain in force against Unita officials based outside Angola.

Earlier on Tuesday the UN Secretary General's special representative for African Affairs, Ibrahim Gambari, arrived in Angola to witness the signing of the ceasefire agreement.

The BBC's correspondent in Luanda Justin Pearce says Mr Gambari's discussions with the government are likely to determine what role the international community might play in the transfer of rebel troops into the Angolan armed forces.