France was reported today to have begun supplying light weapons and ammunition to President Oueddei Goukouni of Chad, increasing French involvement in efforts to get Libyan intervention troops out of the war-ravaged central African country.

The arms supplies, confirmed unofficially by French sources, coincide with a strong French effort to have the Organization of African Unity dispatch peace-keeping troops to Chad in hopes of replacing the Libyan intervention force estimated at nearly 10,000 men. They underline more clearly than before that the new Socialist government of President Francois Mitterrand is prepared to play an active role in pressuring Libya's Col. Muammar Qaddafi to withdraw his troops from the former French colony.

Mitterrand appealed last week from the Cancun North-South summit conference for dispatch of the OAU peace force "without delay." In response, Kenyan President Daniel arap Moi, the current OAU president, pledged to get the troops on their way soon and President Shehu Shagari of Nigeria joined Senegal in offering soldiers for the OAU force.

Secretary of State Alexander M. Haig Jr. also endorsed the French efforts and offered U.S. aid. His backing fit in with a pattern of increased American determination to resist Qaddafi's influence in Africa since the assassination of president Anwar Sadat of Egypt.

Asked about the apparent contradiction between France's support of a peace-keeping force backing Goukouni, and the support two other U.S. allies, Egypt and the Sudan, are giving the rebels of former Chadian defense minister Hissene Habre, a State Department source said the U.S. priority is the removal of Libyan forces from Chad. The source said the United States, France, Egypt and the Sudan all are "in complete agreement" that "the presence of Libyan forces is a very destabilizing factor."

The determination to resist Qaddafi's influence in Africa also underlies much of the French eagerness to get Libyan troops to withdraw. A number of leaders in former French West African colonies have expressed concern to Paris over Libyan-inspired subversion in their countries, French officials say. In addition, the Mitterrand government is seeking to dispel doubts among its African allies sown by former president Valery Giscard d'Estaing's decision last year to stand aside when Qaddafi dispatched his intervention force into Libya to tip a long-festering civil war in Goukouni's favor.

Mitterrand's increased concern also flowed from more immediate developments in Chad, according to reports here today. Qaddafi earlier this month hinted to Goukouni that Libya would withdraw support of his National Union Transition Government unless he agrees to go ahead with a merger with Libya announced last year but never consummated, these reports said. Should Goukouni balk, Qaddafi reportedly said, Libyan intervention forces could back the irregular troops of Foreign Minister Ahmed Acyl, dooming Goukouni's leadership.

This menace was taken seriously in Paris -- and among Mitterrand's aides in Cancun -- in light of Libya's intervention on behalf of Acyl's private army during recent clashes with Goukouni's troops at Mongo in central Chad about 250 miles east of Ndjamena, the capital.

Following a visit here by Goukouni last month, Mitterrand's government appears to have decided to back him as the best force around which to form a national government and unified Chadian Army.

In an interview published today by the Paris newspaper Le Monde, Goukouni emphasized that Libya's intervention forces are in Chad at the request of his government and that "they cannot leave until security is restored." At the same time, he accused the Libyan troops of "committing certain errors" and called on them to "renounce any partisan attitude in the country's internal affairs."

This was seen as a reference to Qaddafi's reported threats to throw his support to Acyl, a public version of diplomatic reports reaching Paris from Chad that are said to have set off the alarm bells in Cancun last week and prompted Mitterrand to make his appeal.

Qaddafi himself added to French concern in an interview on Italian state television Friday night in which he said "unfortunately" he will not be able to withdraw his troops by the end of the year as previously announced.