BANGUI: Central African Republic President Francois Bozize will refuse to leave power during talks with rebels, his spokesman said on Thursday, rejecting the insurgents' main demand and raising the prospect of a return to fighting.

The Seleka rebel alliance, which has accused Bozize of reneging on a past peace deal, advanced to within striking distance of the mineral-rich nation's capital this week before bowing to international pressure to start negotiations.

A week before those talks were due to start, a spokesman for Bozize's ruling KNK party said the president's departure would not be on the agenda.

"The question of President Bozize leaving ... will be rejected systematically if it is proposed," Cyriac Gonda told Reuters.

"For us, the solution is to form a unity government with everyone," he added, reiterating a previous offer by Bozize to give government posts to the rebels.

The spokesman for the CPSK, one of the rebel groups that form Seleka, said on Thursday a peace deal would not be possible without Bozize's unconditional exit.

The advance by Seleka, an alliance of five armed groups, was the latest in a series of revolts in a country at the heart of one of Africa's most turbulent regions.

CAR remains plagued by poverty and underdevelopment despite its reserves of diamonds, gold and other minerals.

French nuclear energy group Areva mines the country's Bakouma uranium deposit - France's biggest commercial interest in its former colony.

Seleka fighters have swept aside regionally-backed government defences to within 75 km (45 miles) of Bangui since launching their assault on Dec. 10.

African leaders are organising peace negotiations in Gabon's capital Libreville that are expected to take place on Jan. 10. The United States, France and the European Union have urged both sides to reach a political solution and spare civilians.

Martin Ziguele, a former prime minister and now a leading opposition figure in CAR, said on Thursday Bozize's departure should be considered during the Libreville talks.

"There will be no taboo subjects in Libreville, all options will be on the table," he said.

Bozize came to power in a Chadian-backed rebellion in 2003 and has since relied on foreign military help to fend off a series of smaller insurgencies. He won elections in 2005 and 2011 despite opposition complaints of fraud.

Regional leaders have supplied Bozize with hundreds of troops - mostly from Chad but also from Congo, Gabon and Cameroon - to shore up the CAR army.

France, which used air strikes to defend Bozize in 2006, refused Bozize's request for military help this time. Paris has 600 troops in the country to defend about 1,200 of its citizens living there.

Residents in the crumbling riverside capital Bangui said they were relieved that peace talks would take place - putting off a widely-feared rebel assault on the city - but were worried the negotiations would ultimately fail.

"It will bring back the war if people try to force (Bozize) to leave," said Pati Bozo, a pensioner. "Bozize was elected ... This is the point that will bring problems."

Central African Republic is one of a number of countries in the region where U.S. Special Forces are helping local soldiers track down the Lord's Resistance Army, a rebel group which has killed thousands of civilians across four nations.