An eastern Chad town that is a hub for aid workers helping Darfur refugees remained under threat Monday from rebels who briefly held it over the weekend, a French military officer said.

Also Monday, the U.N. said looters plundered around $1.5 million worth of aid intended for refugees after rebels briefly seized Abeche. The U.N. High Commissioner for Refugees and the World Food Program issued a joint statement calling for the "rapid restoration of order."

Chadian rebels have clashed sporadically with the government since 2005 and launched a failed attack on the capital in April. The competition for power has become more intense since Chad, a former French colony, began exporting oil in 2004. The rebels have been able to exploit volatility in neighboring Sudan, establishing rear bases in Sudan's troubled Darfur region, which borders eastern Chad.

U.N. and other agencies based in Abeche deliver aid to 218,000 Darfur refugees and some 90,000 Chadians displaced from their homes by the unrest.

The town was seized Saturday by the rebels opposed to President Idriss Deby, who first took power at the head of his own rebel army in 1990. Government forces recaptured the town Sunday, according to officials. The looting by residents took place during the unrest, said the U.N.

Click here to go to FOXNews.com's Africa Center.

French troops, who have a base in the area 550 miles east of the capital, N'djamena, deployed to protect the airport and some 150 foreigners seeking refuge in an aircraft hanger. "We are in a state of war," French officer Didier Lebailly told reporters and aid workers who arrived on the first flight into Abeche since rebels briefly held the town.

He said Abeche still is under threat "from all sides." French troops in jeeps mounted with machine guns patrolled the perimeter of the airport in case of attack.

In Paris, French Foreign Ministry spokesman Jean-Baptiste Mattei said France "firmly condemns this new attempt to destabilize the legitimate authorities."

"These new rebel attacks show again the gravity of the situation and the urgency for an international presence to be deployed along the border between Chad and Darfur," he said.

According to initial reports from staff, more than 500 tons of food worth $500,000 was taken from a WFP warehouse in the center of Abeche. Also stolen was around $1 million worth of blankets, tents, stoves, medical, communications and water purification supplies and other equipment.

"Stealing food from people who have lost everything is the most shameful and inhumane act that anyone can possibly commit," WFP Executive Director James Morris said in a statement.

In the capital, heavily armed Chadian soldiers reinforced their positions Monday, although the government insisted that their forces were pursuing the rebels in the east back toward the Sudanese border. Troops were positioned throughout the capital, cordoning off key government buildings and supported by at least a dozen tanks guarding the main entrances to the city. Schools have been closed and residents of N'djamena have been panic buying.

At dawn, a French Mirage fighter jet conducted low-level reconnaissance flights over the capital and surrounding areas.

Both France and Britain have issued warnings of reports of rebel forces heading toward the capital, urging against all travel to Chad. The Chadian government has denied rebels were about 250 miles from the capital and said they were no longer advancing.

Besides the rebellion, Chad's government has recently reported violence pitting ethnic Arab Chadians against ethnic African Chadians, mirroring clashes in Darfur. Chad accused Sudan of instigating the clashes. Chad often accuses Sudan of supporting Chadian rebels and Sudan makes a similar accusation against Chad.

In Darfur, ethnic African tribes accusing the central government of neglect launched a rebellion three years ago, following years of low-level tribal clashes over land and water. The government is accused of responding by unleashing ethnic Arab tribal militias who have been linked to atrocities.

More than 200,000 people have died and 2.5 million have been displaced since fighting began in Darfur in early 2003.

Chad, an impoverished country in central Africa, has suffered from years of political turmoil that have hampered economic development. The economy relies on livestock and a relatively new oil industry.