Oil fuels ethnic violence in Chad

(CNN) -- The violence in Chad has opened up a new conflict next to Sudan's wartorn Darfur region, where more than 200,000 people have died since early 2003 and 2.5 million people have been chased into refugee camps.

A $300 million international aid mission supporting millions of people in the north African country is now at risk, while the deployment of the European Union's peacekeeping mission to Chad and neighboring Central African Republic has been delayed.

Chad is no stranger to civil wars and invasions since independence from France in 1960: current president President Idriss Deby himself seized power in a rebel uprising in 1990.

The recent discovery of oil has only stepped up the power struggles in the largely desert country. The latest assault on N'Djamena follows a failed rebellion in 2006. Watch a discussion of possible solutions to conflicts in Africa »

The rebels in N'Djamena are believed to be a coalition of three groups, according to The Associated Press.

The biggest group is led by Mohammed Nouri, an ex-diplomat who defected 16 months ago, and a nephew of Deby's, Timan Erdimi.

They have long been opposed to Deby, whom they accuse of corruption and of giving insufficient support to insurgents in Darfur, some of whom are from Deby's own tribe, the Zaghawa, who are from both Chad and Sudan.

The latest violence started when, according to a French military spokesman, rebels with assault weapons, rocket-propelled grenades and pickup trucks crossed into Chad from Darfur in an effort to topple Deby's government.

Chad's Ambassador to the United States Mahamoud, Adam Bechir, has accused neighboring Sudan of supporting the rebels to destabilize Chad's government. Watch why Sudan is being blamed »

Both the Sudanese and Chadian governments have previously accused each other of fomenting violence in their countries by giving support to rebel groups.

About 240,000 people have crossed the border to Chad to flee the civil war in Darfur, where Sudan's government and government-supported Arab militias have been accused of widespread atrocities against the civilian population.

But according to the U.N. High Commissioner for Refugees, at least 400 people had fled the fighting in Chad's capital and crossed to neighboring Cameroon since Friday.

Helene Caux, a spokesperson for the agency in Geneva, said the refugees had arrived in the Cameroon border town of Kousseri, which is only a short distance from N'Djamena.

The border is divided by a river, and it is unclear if people crossed by boat or by bridge, she added.

The Cameroon authorities told the agency they could face problems providing humanitarian assistance if the refugee numbers swell, she said. She said the agency was sending three of its staff to Kousseri to help the relief effort.

The African Union, meeting in Ethiopia, said it would not recognize the rebels if they seize power, and selected Libyan leader Moammar Gadhafi and Republic of Congo President Denis Sassou-Nguesso to try to broker a peace deal.

In a telephone conversation between Gadhafi and Nouri, the rebel leader agreed to a cease-fire and to talks aimed at implementing a peace and reconciliation agreement, JANA reported.

But rebel spokesman Mahamat Hassane Boulmaye said he had not heard of any cease-fire and did not believe Nouri would agree to an unconditional end to hostilities, AP reported.

The French government said it opposed the rebels' actions. "You cannot try to use force to change a sovereign government," said Nicolas Princen, a spokesman for President Nicolas Sarkozy's office.

The U.S. State Department said it joined the African Union in "condemning the attempt by armed rebels entering from outside the country to seize power extra-constitutionally in Chad."

"We call for calm in the capital and support the AU's call for an immediate end to armed attacks and to refrain from violence that might harm innocent civilians," the State Department said.

In May 2006, rebels got within a mile of N'Djamena before government forces halted them, reportedly with the help of French troops garrisoned there; Deby, denied such aid. His government later gave a top ministerial post to a leader of the rebels. E-mail to a friend

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