Chadian attack helicopters fired rockets at rebel forces around the capital Thursday, and tank fire and mortar rounds echoed through the city as government troops attempted to hold off a rebel attack.

U.S. Senate Majority Leader Bill Frist, left, shake hands with Chad President Idriss Deby in this Friday, Aug. 6, 2004 file photo, while a Chadian soldier looks on in Biltine, Eastern Chad. Rebels made their first attack deep inside Chad, fighting government forces in a central town, a witness and government spokesman said, with just weeks to go before presidential elections. Scores of defectors from the Chadian army have joined rebel groups since October in their bid to overthrow President Idriss Deby. [AP]

French fighter jets based in N'Djamena could also be heard, but it was unclear if they were overhead or just revving their engines at the airfield, an Associated Press reporter said. The sounds of fighting could be heard coming from the north, south and southeast of the city.

Columns of thick black smoke could be seen rising from the center of the city.

The French government has said in the past it will not directly intervene in internal politics, but would provide logistical support to the government.

The fighting began before dawn, when residents of eastern neighborhoods awoke to heavy gunfire, sending panic through the city a day after reports that rebels were marching on the capital.

Government officials were not reachable and the state-run radio played music without any commentary or reports on the situation in the country.

The initial fighting appeared to be coming from a defensive position constructed Wednesday on the road leading into N'Djamena (pronounced IN-jah-MEEN-ah) from the east. The gunfire began about an hour before sunrise.

Chadian troops spilled into the streets and began constructing defenses all around the city on Wednesday after three days of attacks in the countryside by rebels and unconfirmed reports that a rebel column has moved to within 60 miles of the capital by late Wednesday afternoon.

French troops based in Chad also took up positions around government office buildings late Wednesday in anticipation of a potential rebel attack. Residents stocked up on food and water.

While it was unclear whether the rebels had enough numbers to overthrow the government, there have been several coup attempts against President Idriss Deby and there was some question about the loyalty of his troops, since the rebels were being led by former army commanders.

The rebels' first attack deep inside Chad came Tuesday in the central town of Mongo, just three weeks before a presidential election scheduled for May 3. There were no casualties, officials said.

France, which supports Deby's government, responded by adding 150 troops to its contingent of about 1,200 already in Chad to protect about 1,500 French citizens there.

Scores of defectors from the Chadian army have joined rebel groups in their bid to overthrow Deby, who himself seized power in a 1990 coup and has seen his authority undermined by violence in neighboring Sudan and an apparent struggle for control of newly discovered oil reserves.

The troubles in Chad have revived fears that the Darfur conflict in neighboring Sudan has the potential to undermine the entire region where Sudan, Chad and the Central African Republic meet.

Decades of low-level tribal clashes over land and water in Darfur erupted into large-scale violence in early 2003 when ethnic African tribes took up arms, accusing the Arab-dominated central government of neglect. The government is accused of responding by unleashing Arab tribal militias known as Janjaweed to murder and rape civilians and lay waste to villages ¡ª a charge it denies.

Sudan has accused Chad of harboring Darfur rebels, while Chad has said Sudan backs Chadian insurgents.

The instability in the lawless border region has made it easier for rebels to organize. The crisis has sent an exodus of Sudanese refugees into Chad, and Deby has been accused of doing too little to help Sudanese in Darfur who share ethnic links with many Chadians.

Since October, the rebels have been skirmishing with government forces along the western border, which is more than 600 miles east of the capital, N'Djamena.

The leaders of Sudan and Chad signed a Feb. 9 peace agreement to end increasing tension over Darfur but it has yet to resolve the chaos on the ground.

In Paris, Foreign Ministry spokesman Jean-Baptiste Mattei said France condemns all efforts to seize power by force and called Chad an "anchor for the stability of the continent as a whole."

Troops from France, which is one of Chad's largest financial supporters, in the past have protected humanitarian workers in eastern Chad who are helping Darfur refugees.

Chad, an arid country three times the size of California, is home to about 10 million people, mostly of Arab origin. The country became independent from France in 1960, but has been wracked by conflict for most of its history.