Chad's escalating civil war is turning into an international confrontation, with France and Libya as the major foreign players. Libyan-backed rebels of former President Goukhouni Woddei are sweeping down from the north in a major attempt to overthrow the government of Hissein Habre. To stop them, France - the former colonial power in the north-central African nation - has moved quickly to supply President Habre with modern weapons, troop trucks, fuel, and spare parts, as well as an undisclosed number of ''civilian experts.''
''France must repeat,'' President Francois Mitterrand warned recently on a trip to Cameroon, ''that it cannot accept reckless actions that would make Chad fall prey to foreign adventures.''
Libyan leader Muammar Qaddafi's next move is unknown, but some think he may send his troops into Chad - just as he did in 1980.
''We have no intention of intervening,'' he told the French newspaper Le Matin. But he warned that ''all foreign intervention in Chad will be considered by us as an act of war against Libya,'' adding that he thinks the United States is trying to broaden the conflict by pushing Zaire, Sudan, and Egypt to intervene.
As his forces continued to battle the rebels in fierce fighting in the north this week, Mr. Habre appealed for direct military backing from France. ''We have asked and we insist for France to participate at our side to repulse this external aggression.''
French Foreign Ministry officials declined to comment on Habre's request except to reiterate an earlier statement that France would not send troops. The officials are worried about being dragged into a civil war which has been simmering for almost 17 years now.
But the French are also worried about Libyan adventurism and a possible escalation on Mr. Qaddafi's part. The Libyan leader has long talked of creating a Pan-Islamic empire stretching across the Sahara, and French officials say installing Mr. Woddei as Chad's leader would be a first step toward this goal.
Such a design would threaten Egypt and the Sudan. Both countries have joined France in announcing that they are prepared to ''take measures'' if the Libyan-backed intervention of Chad continues. And this week Zaire sent 250 paratroopers to Mr. Habre's aid.
Libyan meddling in sub-Sahara Africa also scares Francophone West Africa. But most of West Africa is looking to France for protection from the Libyans. According to the French newsweekly Le Point, the President of Guinea, Ahmed Sekou Toure, telephoned the Elysee Palace in Paris last week and reminded a top adviser to President Mitterrand, ''France has its responsibilities with regard to its former colonies.''
Washington also wants France to take the lead in checking Mr. Qaddafi, American diplomats here said. Even before the Quai d'Orsay, the State Department had accused the Libyans of meddling in Chad, and US warplanes were sent into Libyan-claimed airspace to warn Mr. Qaddafi.
But on the whole, America has stayed aloof, quietly praising French intervention. ''The area is in France's traditional sphere of influence,'' one American diplomat here explained, ''and we do not want to turn Chad into the site of a full-scale East-West confrontation.''
If Chad's conflicts were only internal, the world probably would quickly forget them. Chad is largely desert and has few natural resources. Its population of some 4.7 million people are among the world's poorest, struggling to avoid starvation from the droughts that have ravaged the country in recent years.
Politically, too, Chad is a sad story. Since it became independent in 1960, it has lapsed into civil war after civil war. The basic division is between the Muslim north and the Christian and animist south. But personal and tribal animosities have played a larger role in recent developments.
In 1980, the Libyan troops helped to install Woddei in power. But when international pressure and a desire by Qaddafi to become chairman of the Organization of African Unity moved the Libyan leader to withdraw his troops in November 1981, Mr. Habre drove Woddei into exile. Some alleged Habre had help from the US Central Intelligence Agency, among others.
Last October, Qaddafi brought Woddei to Tripoli. There the deposed Chad leader announced the formation of a government in exile. With Libyan help, according to French officials, he put together an army of about 4,000 men.
Late last month his troops were ready. They attacked the northern oasis town of Faya-Largeau, easily routing its defenders. French officials say Woddei was supplied by the Libyans, but that no Libyan troops were involved in the battle. An Agence France-Presse report this week, though, said that about a dozen Libyans were assisting the rebel troops. Others have reported more than 1,000 Libyans may be involved. The rebels this week are reported to be battling government forces near Abeche and Oum Chalouba.
So far, Paris has limited its aid to supplies and advisers.
Now Woddei's troops appear to be once again advancing on the capital of N'Djamena, raising the possibility that the 1978 scenario may be repeated. Considering Chad's history and its rambunctious northern neighbor, however, even the French admit that intervention this time around is no more likely to create a lasting peace than the last time.