JOHANNESBURG - Rebels on Thursday inched closer to the capital of the Central African Republic, one of Africa's most fragile states, threatening to topple an elected government that has had an unsteady grip on power for nearly a decade.

Thousands of civilians fled cities and towns into dense forest as embassies and aid organizations evacuated many of their staff members from the capital, Bangui.

The rebel group, an amalgamation of several different factions fighting under the name "Seleka Coalition," is trying to remove President Francois Bozize, a military officer who seized power in 2003 and has twice since been elected president. The rebels accuse him of failing to live up to the terms of peace agreements signed beginning in 2007 to quell several uprisings.

The rebels have trounced government forces in the country's central and northern regions, taking numerous towns and chopping away at the distance between them and a potential overthrow in Bangui, the seat of one of Africa's weakest governments.

The country is between some of the most unstable nations on the continent: Chad and South Sudan to its north and east, and the Democratic Republic of Congo to the south. Joseph Kony, leader of the Lord's Resistance Army and the focus of a global manhunt, is believed to be hiding in the forests of the southeastern Central African Republic.

Caught in the middle of this maelstrom are the country's nearly 5 million civilians, who have been forced to flee their homes for the deep cover of the forest dozens of times over the past five decades.

"The population is extremely worried, because the rebel advance has moved quickly in a short matter of time, and the army is moving backwards," said Sylvain Groulx of the relief group Doctors Without Borders.

The mass exodus raised the specter of a humanitarian crisis.

"You have a population that under the best times of peace have alarming rates of mortality, some of the worst sanitary conditions in the world; health indicators are extremely bad," Groulx said. "Now, all of a sudden, when there is fighting, they are out into the field."

Protesters threw stones and tore down the French flag at the French Embassy, demanding that the former colonial power do more to thwart the rebel advance.

France, which maintains a contingent of about 250 soldiers near Bangui as part of a multinational peacekeeping force, has made clear that it does not intend to be drawn into the conflict, despite requests by Bozize.

Only under a U.N. mandate would France consider a non-peacekeeping intervention in the Central African Republic, French President Francois Hollonde said Thursday.

The landlocked republic has plenty of natural wealth, but its history of violence, repression and bad government has left its people among the world's poorest. It has known little peace since it won independence from France in 1960.