Peace talks between the government of the Central African Republic, the Seleka rebel alliance and opposition parties have opened in Gabon.
The talks were organised by regional governments, the UN and the US.
Officials say the negotiations were delayed by two hours by the late arrival of the rebels, who have seized control of the north and east of the country in a four-week offensive.
They accuse President Francois Bozize of breaking previous peace deals.
The chairman of the talks, Congolese Foreign Minister Basile Ikouebe, said that at the opening session he wanted the three parties to focus on renegotiating those accords.
But the rebels have demanded the resignation of Mr Bozize, who is not attending the talks.
Speaking to the BBC from Bangui, the capital of the CAR, Mr Bozize he would not step down.
"That would be a betrayal of my country. That would betray the people who elected me", he said.
"This is the defence of democracy, the defence of the constitution. To do nothing says we're turning to the law of the jungle."
The rebels only halted their advance 100km (60 miles) from Bangui after a regional peacekeeping force was deployed, but Mr Bozize denied he was negotiating from a position of weakness
He accused the rebels of being backed by outside interests, saying: "We have the people with us and that is the most important thing. Those who have come are foreigners and sooner or later the people will rise up against them."
It is the biggest threat Mr Bozize has faced since he took power in a coup in 2003.
Both the US and France, the former colonial power, rejected pleas by his government for help to defeat the rebels.
France, however, despatched additional troops to the country to protect its nationals, many of whom work in Areva's large uranium mine at Bakouma in the south-east of the country.
CAR remains one of the poorest countries in Africa despite considerable mineral resources.