France, anxious to play down its colonial reputation as the gendarme of Africa, has rejected pleas from Chad for the immediate dispatch of French troops to counter a threat by Libyan-backed rebels.

The French government has reacted to the latest flare-up in the civil war in its former African colony by sending planeloads of military supplies to bolster the embattled government of President Hissene Habre. But senior French officials have insisted that France will not send any soldiers to Chad despite evidence of Libyan, and possibly Eastern European, involvement in the conflict.

The latest call for French military intervention came from Chad's foreign minister, Idriss Miskine, on a stopover here last night on his way to China. He said Chad was living through "a dramatic time" and accused the Soviet Union of encouraging what he called "Libyan expansionism."

Describing French aid so far as "insufficient," Miskine said that "if France wants to safeguard its friends and relations, it must intervene immediately in Chad because history will judge its actions."

The new crisis in Chad, which began in late June when rebels led by former president Goukouni Oueddei mounted an offensive in the north, has exposed a dilemma facing France's Socialist government in its relations with Africa. While President Francois Mitterrand is eager to play his part in shoring up western influence on the continent, he wants to avoid getting entangled in drawn-out neocolonial conflicts that could damage France's reputation in the Third World.

"We are not going to react like the United States in Honduras or in Nicaragua," Foreign Minister Claude Cheysson stressed last month.

The remark prompted the influential Paris daily Le Monde to comment that the fear of such a comparison with the United States had led Mitterrand to take the risk of "weakening France's credibility in a region where many of its friends rely on it for their defense."

French policy-makers appear to have won a breathing space because of a strong government counteroffensive. After a series of defeats, forces loyal to Habre have retaken the eastern town of Abeche and the oasis of Oum Chalouba.

The respite, however, may prove short-lived as Goukouni's forces are still solidly entrenched in the northern town of Faya Largeau, from where they control about a third of the country. In an interview with a French journalist this week, Goukouni said he was consolidating his position before continuing a drive on the capital, Ndjamena.

According to French press reports from Chad, the rebel army has firepower superior to Habre's forces and is directly supplied from Libya. Chadian officials have charged that Libyan and even East German military "experts" are serving in Goukouni's army and helping to operate sophisticated Soviet-built 155-mm artillery.

Officials in Paris insist that France will carry out "to the letter" its obligations to Chad under a military cooperation agreement signed in 1976. The agreement provides for the possibility of logistical assistance to the Chadian Army but rules out sending French soldiers.

France is reported to have flown 200 tons of military supplies, including artillery pieces, armored cars, machine guns and rifles, into Chad during the past two weeks. Many chartered U.S. aircraft have also been seen arriving at Ndjamena.

A senior French official, who asked not to be named, said there was no question of France reneging on its commitments to other former African colonies with whom it has formal defense treaties. He confirmed earlier press reports that, shortly after coming to power in May 1981, Mitterrand authorized a clandestine military intervention in Cameroon in West Africa to forestall a threatened invasion by Nigeria.

The official refused to give further details about the operation except to say that it was carried out under the cover of repatriating Cameroonians from neighboring Gabon and involved French ships. The report could not be confirmed.

France's refusal to send troops to Chad or provide air cover for Habre's forces from its base in Gabon has been criticized by some opposition leaders. A former Gaullist prime minister, Pierre Messmer, said in a television interview that the dispatch of modern weaponry without men was practically useless since Habre's 4,000 or so soldiers were insufficiently trained.

In fact, both French and U.S. sources insist that a limited number of French military experts have been sent to Chad under the guise of civilian advisers. A journalist reporting for the weekly magazine Le Point said that a dozen such technicians with military-looking hairstyles were seen near the airport attempting to give Chadian soldiers a crash course in using French-made 106-mm, jeep-mounted guns.

A spokesman for Goukouni's forces here said 51 French soldiers were aiding government troops in intelligence gathering and logistics. French officials formally deny that any French soldiers have been sent to Chad.

The major foreign support for Habre has come from Zaire, which has promised a force of nearly 2,000 men. A second contingent of Zairian soldiers flew into Ndjamena today to reinforce the 250 paratroopers who arrived on July 3. Zaire also has sent three French-built Mirage fighter-bombers and three Italian-built Macchis.

French reluctance to get too involved in Chad can be explained partly by the complicated nature of Africa's longest running postcolonial civil war. Habre and Goukouni, who both belong to the northern Toubou tribe, have fought with and against each other for much of the past decade and alternated in and out of power.

French troops remained in Chad after it became independent in 1960 and withdrew only in 1980. Successive French presidents sent soldiers to Chad but were unable to prevent fighting between tribes in the country.