BANGUI: Central African Republic government and opposition delegations left on Tuesday to join rebels for talks later in the week in the Gabonese capital Libreville to end the conflict in their volatile nation.

A delegation of the rebels who have seized key towns in the impoverished country arrived Monday, while government, opposition and civil society representatives left Bangui early Tuesday, a government official said.

Congo Republic President Denis Sassou Nguesso, who is serving as mediator, has said the peace talks could open later this week, while sources said some one-on-one meetings could take place earlier.

The head of the government delegation, Jean Willybero-Sako, voiced confidence that concessions that Central African President Francois Bozize has made so far -- he has proposed a national unity government and said he would not try to seek an unconstitutional third mandate -- would go a long way toward resolving the conflict.

The concessions "cleared a lot of obstacles," Willybero-Sako told AFP on Sunday. "That showed a certain willingness to go forward, to take into account everyone's concerns."

Minister of Territorial Administration Josue Binoua has said the government would also propose "army reform, an economic stimulus plan and the implementation of a new electoral code" at the talks.

Asked about a persistent rebel demand that Bozize step down, Willybero-Sako replied: "We have struggled -- rebels, opposition and government -- to provide our nation with a constitution that everyone now wants to see respected."

Bozize, a former army general, came to power in a coup in 2003 and has been voted back into office twice, in 2005 and 2011.

He has been suspected of wanting to modify the constitution to be allowed to seek a third term in 2016.

Bozize made a quick trip Monday to Brazzaville to meet with Sassou Nguesso.

At a joint press conference afterward, Sassou Nguesso stressed that a "military solution was not a good one and there must be negotiations."

Bozize, who will be present in Libreville but will not attend the talks, claimed the rebel movement was triggered by "elements coming from outside."

He added: "We consider them as mercenaries manipulated from outside, who attacked the peaceful Central African people."

The rebels have insisted that the departure of Bozize, who has been in power since 2003, should be up for discussion at the talks -- and Sassou Nguesso said the issue would be addressed.

"We cannot interpret, in our role as mediator, the statements of one or the other" side, he said, adding that "all parties have agreed to go to negotiations in Libreville and we will address all these questions among brothers."

Rebel chief Michel Djotodia, who made no statement on arrival in the Gabonese capital on Monday, told AFP earlier on a stopover in Chad: "One doesn't make war without also looking for peace."

The Seleka alliance of three rebel movements launched its assault on December 10 in the north of the Central African Republic, a mineral-rich country of of five million that is notorious for coups and army mutinies.

Since then, it has moved steadily south, capturing a string of key towns with little or no resistance from the poorly equipped and poorly trained army.

They are now in striking distance of the capital Bangui, near Sibut, 160 kilometres (100 miles) to the north.

At first, the rebels were simply calling on the Bangui government to respect the terms of peace accords signed in 2007 and 2011. As their position strengthened, however, they began calling for Bozize to step down.

The Economic Community of Central African States (CEEAC) will host the Libreville talks. But the regional bloc has also sent more troops to strengthen FOMAC, its multinational intervention force in the CAR.

They are deployed as a buffer force at Damara, 75 kilometres north of the capital Bangui.