Disarmament of Mr Savimbi's 75,000 National Union for the Total Independence of Angola (Unita) troops, the confinement to barracks of government security forces, and the formation of a single 70,000-strong national army remain the key stumbling-blocks.
Failure to resolve those issues torpedoed Angola's previous peace agreement after Mr Savimbi rejected his defeat in the October 1992 UN-observed general elections and restarted the conflict, which erupted in 1975 on the eve of independence from Portugal. From 1992 to 1994 the war claimed 500,000 lives, reduced the central cities of Huambo and Cuito to rubble, and forced a third of the nation's 10 million people to become dependent on international food aid.
Angola's parliament created two new vice-presidential posts last month, but the ruling Popular Movement of the Liberation of Angola (MPLA) has said that Mr Savimbi cannot take up the offer of vice-president for economic affairs until his army is disarmed.
The meeting on Thursday was the second following their May summit in Lusaka, Zambia, where the two rivals ratified a UN-brokered peace agreement signed last November, after the government army had routed Unita from its central highland stronghold in Huambo. The fact that the talks had to be held in the West African nation of Gabon - Mr Savimbi still fears for his life in Luanda - underlined how far Angola still must travel before a genuine peace takes hold.
There have been repeated, though relatively small, clashes between government troops and Mr Savimbi's rebels, especially in the north-eastern diamond producing areas, in recent weeks, prompting the armed forces chief of staff, General Joao de Matos, to warn that a return to war was "in the air".
Ironically, hopes for a lasting peace could reside in the hands of Gen de Matos, a charismatic 38-year-old veteran of Luanda's years of battles against Unita and its former South African allies. With the help of South African mercenaries, many of whom once fought alongside Unita, and massive arms purchases, he rebuilt an Angolan army that had effectively collapsed after the 1992 elections and had allowed Unita to take control of two- thirds of the country.
Known to be suspicious of both Unita and the MPLA, General de Matos ignored demands by the UN and the Clinton administration last November to halt an offensive against the rebel headquarters in Huambo, and broke Unita's traditional stranglehold on the Central Highlands. That humiliating defeat, combined with declining revenues for smuggled diamonds and increasing diplomatic isolation, forced Mr Savimbi to retreat to the village of Bailundo and to authorise his negotiators to sign the peace deal in Lusaka.
The UN Special Representative, Alioune Blondin Beye, capitalised on Unita's unprecedented military weakness to broker the deal and to convince a UN Security Council still feeling the sting of the 1992 debacle to authorise millions of pounds in funds and the dispatch of blue helmets to secure the peace.
But fewer than half of the expected 7,500-strong peace-keeping force has arrived in Angola, efforts to remove millions of landmines are months behind schedule, and indications are that government security forces remain on alert.