Updated

Hundreds of civilians have died in fierce fighting between rebels and government forces in Chad's capital, Red Cross officials said Tuesday, as the insurgents agreed to a cease-fire and their momentum faded. Former colonial power France threatened to enter the fight to support the government.

Chad's government told the French military it still was fighting rebels using "air power" outside of N'Djamena, the capital, according to French military spokesman Cmdr. Christophe Prazuck.

Chief rebel leader Mahamat Nouri charged they were being bombarded by French Mirage jets — but France said it had not yet gone on the attack. French intervention in the past helped stave off a major rebel attack in this oil-rich country on President Idriss Deby, accused by the insurgents of corruption and embezzling millions in oil revenue.

Tuesday, bodies lay rotting under a tropical sun in N'Djamena, according to a local reporter who left his home Tuesday for the first time since the rebels entered on Saturday.

Corpses of more than 10 military and civilian victims were sprawled across Avenue Mobutu, a main thoroughfare. The charred hulks of two tanks and several pickup trucks, used by both sides in the fighting, littered the streets.

Most downtown shops and buildings have been looted. Further from the center, the state broadcasting station and the parliament building were stripped by rampaging looters.

The Presidential Palace, which backs onto the Chari River, was off limits, the entrance blocked by tanks and tree limbs. Presidential Guards patrolled outside.

Chad Red Cross officials said hundreds of civilians have died, most from bullet wounds. The officials, who were driving around looking for wounded, said they were too scared to give their names.

More than 1,000 people have been wounded, the International Committee of the Red Cross said.

Soldiers barred the two bridges across the Chari River that divides N'Djamena from neighboring Cameroon on Tuesday afternoon, blocking the escape route for hundreds of civilians, and possibly rebels.

As many as 20,000 people have fled across the river, the U.N. refugee agency said. The Red Cross said the number of fleeing grew steadily earlier Tuesday, and could have reached 30,000.

Chad is in a violent swath of Africa that is home to hundreds of thousands of refugees and borders Sudan's war-ravaged Darfur region. The U.N.'s World Food Program said the violence could disrupt delivery of food to 420,000 Darfur refugees and Chadians displaced by violence.

Chad accuses Sudan of being behind the latest violence in Chad to prevent Europe from deploying a peacekeeping force to the border region, a mission Sudan has resisted. Sarkozy's top aide has echoed that charge. Chad and Sudan have long exchanged charges and denials of supporting the other's rebels.

Tuesday afternoon, Nouri, leader of the biggest of three rebel groups in a coalition, told BBC radio they have accepted a Libyan-brokered cease-fire. Nouri added he did not think the government had accepted. It was not possible to reach the other rebels leaders, who include Deby's nephew and former chief of staff, Timan Erdimi. There was no word from the government.

Nouri said the only condition was "an all-inclusive dialogue that gathers around the same table the armed groups, the Chadian political parties and civil society movements."

Nouri had earlier told French radio Europe-1 that the rebels were ready to launch a new offensive and would be able to take the capital — except for the French army. But there was no sign of fighting in the capital Tuesday and Chadians previously too scared to leave their homes were venturing out, indicating the rebellion was losing steam. Still, Prazuck, the French military spokesman, said the threat to attack again was "serious."

On Monday, the U.N. Security Council, acting on a French request, authorized France and other nations to help Chad's government.

"If France must do its duty, it will do so," French President Nicolas Sarkozy said Tuesday. "Let no one doubt it."

France has 1,900 troops in Chad, Deby has between 2,000 and 3,000 and the rebels from 1,500 to 2,000, according to the French military.

So far, French forces have only been securing the safety of foreigners and the capital's airport and offering logistical, medical and intelligence help to the Chadian military, Prazuck said.

France has had difficulty persuading its European partners to agree to the proposed EU force in Chad and the Central African Republic along the border of Sudan's Darfur. It assured them it would not be used to bolster Deby's government. France is providing the biggest portion of funding for the force and 2,100 of its 3,700 soldiers.

EU deployment would seriously hamper Chad's rebels, and their big push came just as Europe was finalizing deployment of the force, which had been delayed because of lack of equipment.

The fighting prompted the EU to again delay deployment, though officials said the force eventually would be sent.

The delay, though, "holds the risk that it could open up fissures that already exist between (European) member states about cooperating on the mission," said John Kotsopoulos, an analyst at the Brussels-based European Policy Center.

Sudan, which helped Deby's rebel forces seize power in 1990, since has fallen out with the Chadian leader.

While many Chadians may share the rebels' stated grievances against Deby, the uprising has the hallmarks of a power struggle within the military elite that has long controlled Chad. Power has never changed hands at the ballot box here, and the recent discovery of oil makes control of the treasury even more alluring.

Human Rights Watch said it had reports that Chadian security forces had since the rebellion reached the capital detained unarmed political opposition leaders. Amnesty International issued an urgent appeal for four Chadian opposition leaders — none linked to the rebels — it said were arrested on Sunday.