This country's 14 years of civil war between southern blacks and northern Moslems dramatically illustrates how foreign interests can cynically exploit the domestic cleavages that rend many of Africa's young nations.

The use to which revolts in a country like Chad, where ethnic tribbal and religious fissures run deep, can be put by more powerful outsiders and neighbors has been a particularly touchy issue in the two decades of black Africa's independence.

One illustration was last summer's Organization of African Unity summit in Liberia, where members were obviously dismayed by the constant fighting in Chad and refused to seat either of two competing Chadian delegations. But the delegates also were unable to resolve the delicate issue of how to keep African domestic upheavals from attracting outside interference or spilling across borders.

In its two decades of precarious independence, Chad has been torn by fighting between the equally divided Christian blacks of the southern part of the country and the northern Moslems. But it has also been the target of two competing powers in the region, Islamic Libya and the former colonial power, France.

France, throughout the last two decades, intervened in Chad financially and militarily to support a corrupt and dictatorial government dominated by the black southerners as it unsuccessfully attempted to brutally smother a rebellion by Chad's moslems.

The French poured millions of dollars worth of aid, combat troops and Mirage jets into Chad during the civil war. But by last year France, "had washed her hands of the southerners," because of their unwillingness to reform, according to a Western source. France then took a neutral position and after bloody fighting the southerners' 6,000-man Army retreated from Ndjamena last February.

Since the southerners' defeat, France has tried to portray itself as the neutral peacekeeper in Chad, while turning tables and favoring Moslem guerrilla leader Hissene Habre among the officials of the 10 divided Moslem groups, according to Western sources. Habre is known for his anti-Libyan stance.

Libya, however, has been clandestinely supporting several fundamentalist Moslem factions in the new transitional government. And in a move characteristic of enigmatic Libyan leader Muammar Qaddafi, it has also backed the defeated, but still intact army of southern blacks led by Col. Wadal Abelkader Kamougue. Throughout the civil war, Qaddafi supported a shifting alliance of the Moslem factions, most of whom are enemies of Kamougue.

Qaddafi's support for Kamougue, who had the reputation for brutal treatment of Moslems during the war, reportedly grows out of Kamougue's hatred for Habre.

The Moslems, who began the revolt in the mid-1960s after being excluded from power and subject to unfair taxation, split into numerous factions as the revolt spread. Libya, which supported the northern desert Moslem nomads, claimed parts of Chad based on precolonial ties and in 1973 occupied the reportedly uranium-rich Aouzou Strip across its southern border with Chad. The southern-dominated government at the time said nothing about the annexation, supposedly in exchange for a Libyan promise to withdraw aid from the Moslems. Libya did not withdraw its support, but still remains in control of the area.

The Moslem factions have a total estimated strength of 20,000 troops, some of which reportedly were trained by North Korean. But each controls its own area and the contentious factions have different aims and are jockeying for power.

Qaddafi is supporting the Moslem fundamentalists, who want to create an Islamic republic much like Iran's, as the first building block for a pan-Islamic, Libyan-controlled swath across the northern Sahara, several knowledgeable African sources said.

One of Qaddafi's aid recipients, Chadian Foreign Minister Ahmat Acyl has 1,500 of his guerrillas training in Libya, a Western source revealed.

Meanwhile, France has kept a 1,200-strong paratroop force in this capital to help maintain the fragile peace.

France is spending $1 million a day to stay in Chad, a country of marginal economic importance, but observers said the French see the country as essential to their interests in Central Africa.

"The money they have put into Chad can never be replaced," said one informed source about the French. "But they see their presence in Chad as strategic to their interests."

David Dacko, the French-installed president of the Central African Republic, was flown from Ndjamena in September accompanied by French paratroopers on the night those same soldiers toppled the government of self-styled Emperor Jean-Bedel Bokassa.

Ndjamena also gives the French "flexible movement" to future possible trouble spots in French-speaking Africa, the same sources said, such as Kinshasa, Zaire, Libreville, Gabon, and Brazzaville, Congo.

The French forces may be leaving here soon, however, as part of an agreement to be replaced by a three-country African peacekeeping force. The first contingent of the three-country force, 400 Congolese soldiers, arrived in mid-January and troops from Benin and Buines are expected soon.