Central African Republic's embattled President Francois Bozize appealed Thursday for French and US help to halt a rebel advance as regional troops were deployed to secure the capital in an escalating crisis in one of the world's poorest countries.

The UN is pulling its staff out and the US has warned its citizens to leave in the face of the deteriorating security situation as rebel fighters close in on Bangui.

But former colonial power France, whose embassy in Bangui came under attack on Wednesday by demonstrators angry at the lack of French help, vowed it would not intervene in the conflict.

"We ask our French cousins and the US, the great powers, to help us to push back the rebels and to allow for dialogue in Libreville to resolve the current crisis," Bozize said in a public speech in Bangui.

"There is no question of allowing them to kill Central Africans, of letting them destroy houses and pillage, and holding a knife to our throats to demand dialogue," said Bozize, who himself seized power in a coup in 2003.

"It is a plot against the Central African Republic, a plot against its people."

The rebel coalition known as Seleka has seized a string of towns in its sweep across the mineral-rich but deeply poor country since its fighters took up arms on December 10.

More regional troops were being sent in to help secure Bangui but French President Francois Hollande said Thursday that France would not use its troops stationed in the country to interfere in the conflict which is escalating despite both sides apparently agreeing to hold talks in Libreville.

"If we are present, it is not to protect a regime, it is to protect our nationals and our interests, and in no way to intervene in the internal affairs of a country, in this case Central Africa," Hollande said. "Those days are gone."

A French foreign ministry spokesman said however that Paris "condemns the continued hostility by the rebel groups" and that the crisis should be resolved through dialogue.

France has around 250 soldiers based at Bangui airport providing technical support to a peacekeeping mission run by the central African bloc ECCAS.

Since the end of colonization in the 1960s, French troops in West Africa have often come to the help of former colonies whose regimes were on the verge of being toppled.

"Bangui is fully secured by the troops" of the FOMAC central African military force, its commander General Jean-Felix Akaga said on national radio. "Others will arrive to help reinforce this mission of securing Bangui."

However, a source in Gabon's defense ministry, told AFP that no decision had been taken, while a senior DR Congo army source said, "There is nothing planned to combat this (rebel) movement."

The rebels began their push in early December, charging that Bozize and his government have not stuck to the terms of peace deals signed between 2007 and 2011.

As the ill-equipped and under-paid Central African army proved little challenge to the insurgents, Bozize asked for help from neighbouring Chad, which had helped him during rebellions in the north in 2010.

AFP