French military cargo planes ran a round-the-clock shuttle to this African nation today, bringing in military supplies and forces to bolster the government in its war against Libyan-backed rebels. One French military source said French troops here now numbered more than 700, with more to come.

The civil war has been in a lull since Friday, according to Chadian Information Minister Mahamat Soumaila. There has been no bombing and the country is calm, he said. But it was unclear whether the lull was a reflection of the French intervention.

For the past two days the military situation has been "stationary," Soumaila said.

The French military source, who demanded anonymity, said French Transall military cargo planes landing at Ndjamena's airport had brought the French troop total to between 700 and 800. He declined to specify the maximum that the French government is willing to commit to the aid of President Hissene Habre's government. Another informed source, however, said the number could reach 1,000.

The government of French President Francois Mitterrand originally had said that about 180 soldiers would be sent to Chad to give "instruction" to Habre's troops.

Habre's government has been battling a coalition of rebels since late June in a series of thrusts and counterthrusts across eastern and northern Chad.

The rebels, led by former president Goukouni Oueddei, now control the northern town of Faya Largeau and, from there, the northern third of the country.

The French government decided to intervene in the fighting in early August when planes, allegedly from Libya, began bombing government troops at Faya Largeau in support of the rebels. Government soldiers retreated from Faya Largeau last Wednesday in the face of continuing bombing and the approach of a Libyan armored column.

French troops have now been deployed to the towns of Salal and Abeche. They have orders to fight back if fired upon by either the rebels or the Libyans. The towns control the only two roads to Ndjamena, the capital.

The French military source said that the French have Jaguar jet fighters on alert at their reactivated Bouar base in the neighboring Central African Republic south of Chad.

The buildup of French military equipment continued today with Transalls ferrying in jeeps, cannons and light armored cars from France and the Central African Republic. The shuttle has been running around the clock since Friday.

But Soumaila said the government would need more French aid if Libya and the rebels decide to press their assault and move south to Ndjamena.

Soumaila said Habre repeated his request for direct military intervention by the French in talks with Guy Penne, Mitterrand's chief adviser on African affairs, during Penne's 24-hour visit to Ndjamena. Penne left Chad today for Cameroon.

Soumaila said Habre reiterated to Penne the Chad government's insistence that the French military presence should be stepped up "to the scale of the massive Libyan invasion."

He said Habre told Penne the French Army would be welcome to set up new military posts anywhere it wished on Chadian territory.