France threw its weight behind Chad's President Idriss Deby on Tuesday, saying it could intervene against armed rebels who declared they would only stop fighting if Deby quit.

After obtaining United Nations Security Council backing for Deby's government, French President Nicolas Sarkozy warned the rebels France would do its duty and had the means to respond to any unlawful attack against its former colony.

Chad has accused Sudan of supporting an offensive by the rebels, who stormed into the capital of the oil-producing central African country at the weekend before withdrawing. Khartoum denies backing the rebels.

Rebel leaders accused France's military of fighting in support of Deby. The French, who used troops and planes to evacuate hundreds of foreign nationals from the capital N'Djamena, quickly denied this.

Deby's government says it routed the rebels in the chaotic fighting which left bodies strewn in the dusty streets and hundreds injured. The rebels, who brand Deby's government as corrupt and dictatorial, have said they withdrew to regroup.

A rebel spokesman, Henchi Ordjo, told Reuters they were ready for a ceasefire -- but on condition Deby stepped down. Another spokesman, Abderamane Koullamalah, said they wanted a ceasefire with dialogue, without mentioning Deby's departure.

Chadian Prime Minister Nouradine Delwa Kassire Coumakoye dismissed talk of a truce. A ceasefire, why? We'd agree a ceasefire with who?, he told France 24 television, saying the rebels had fled.

France lobbied for and obtained a non-binding statement from the U.N. Security Council on Monday, which urged countries to support Deby's government against the rebels.

French President Sarkozy said this meant his country could intervene in Chad in support of Deby if need be.

If France has to do its duty, it will, he told reporters during a visit to western France.

The rebel attack forced the European Union to delay the deployment of a peacekeeping force to eastern Chad to protect thousands of refugees from the war in Sudan's Darfur region. More than half of that force will come from France.

FRANCE ACCUSED

Ordjo accused French helicopters and tanks of opening fire on Monday in support of Deby's forces near N'Djamena's airport. France has involved itself directly in the conflict ... they've caused civilian victims, Ordjo said.

French armed forces spokesman Christophe Prazuck denied this, but said French forces had been caught up in skirmishes and they fired back. It was legitimate defense, he added.

In N'Djamena, government troops backed by tanks and helicopters were guarding the central presidential quarter. People ventured out to try to buy food, but prices of basic goods like rice and sugar had skyrocketed.

Reaffirming French backing for Deby's legitimately elected rule, French Defense Minister Herve Morin said there was no sign of rebel fighters returning to the Chad capital.

Every day and even every hour that passes shows Idriss Deby regaining control of the whole country, Morin told French radio. He said France was not threatening the rebels, but added there was a sort of sword of Damocles hanging over them.

Critics of Deby, a French-trained pilot who took power in a 1990 revolt and won elections in 1996, 2001 and 2006, accuse him of ruling like a dictator. Morin said the 2006 polls, boycotted by the main Chadian opposition, were perfectly democratic.

Taking advantage of the end of the fighting, thousands of refugees carrying children and belongings streamed out of N'Djamena on Monday over the river border bridge into Cameroon.

Those who stayed said they feared for the future.

What a curse for our country ... war has broken out, and at this time as I talk to you, I haven't got anything at home with which to buy food for my children, Gilbert, a civil servant who declined to give his last name, told Reuters.

Sudan