France has told its moderate African allies that, short of a full-scale Libyan invasion of southern Chad, it will not seek to force Libya to honor the troop withdrawal agreement the two nations made in September, according to diplomats gathered here for the 11th annual Franco-African summit.

Aides to President Francois Mitterrand have said that, barring such a move into the south, France is willing to tolerate Libya's continuing military presence in the northern half of the country.

Under the troop withdrawal accord reached with Libyan leader Muammar Qaddafi, France airlifted its estimated 3,500 troops from southern Chad in October and November.

The Libyans lagged, however, and a political uproar developed in France after Mitterrand admitted publicly for the first time on Nov. 16 that Libyan troops remained in the former French colony despite the announcement by both sides six days earlier that the mutual withdrawal was complete.

French officials then reiterated an earlier threat to return French troops to Chad if the Libyans failed to abide by the accord.

Libyan troop strength in Chad is now believed to be about 5,000. Some of those troops are thought to have entered the country fairly recently.

Mitterrand appeared to confirm the new position publicly in a speech today. He told the opening of the two-day summit that France would not tolerate military aggression against any of the African states with which it has mutual defense agreements. But he pointedly noted that Chad was not among those countries.

He said France had voluntarily committed its forces to Chad last year to restore strategic "equilibrium in Africa." He also indicated he believed that the mission had been accomplished.

Critics at this conference charged Mitterrand in effect has decided to allow Qaddafi to renege on the withdrawal agreement and has decided to acquiesce to the de facto partition of Chad between the government of President Hissene Habre in the south and Libyan-backed rebels in the north.

"He's leaving Habre to twist slowly in the wind," said a diplomatic observer here.

An official French spokesman tonight recounted to reporters some of what the leaders said in this afternoon's closed-door session. The spokesman said Habre reminded the leaders that his nation was "cut in half," blamed Libya for the continuing conflict and made an impassioned plea for aid from France and other African nations.

The spokeman said Mitterrand, in response, defended France's role in Chad and denied he favored partition of the country. But Mitterrand added, according to the spokesman, "France is ready to take risks, but not useless risks."

French officials insist that their goal is still a Libyan pullout, which they will seek to achieve by diplomatic means.

French Foreign Minister Roland Dumas underscored this today when he denied France had acceded to partition.

"I formally deny the contention the French government accepts the principle of maintaining Libyan forces in the north of Chad," he told the French news agency Agence France-Presse.

French officials have told reporters here that Mitterrand is determined to avoid a military confrontation with Qaddafi.

They have cited domestic political considerations, saying the French public would not tolerate what could become a drawn-out and expensive conflict in Africa at a time when the French economy is slumping.

Moderate African leaders from French-speaking nations privately have expressed their dismay over Mitterrand's decision.

Chad's Habre sat impassively during Mitterrand's speech today and did not join in applause at its conclusion.

Ivory Coast President Felix Houphouet-Boigny, the senior Francophone African leader who repeatedly has voiced fears about Libyan expansionism, chose not to attend this summit in part to protest the French position.

Zaire's Mobuto Sese Seko, who originally told reporters that he also would boycott the meeting, changed his mind at the last minute, reportedly at the personal urging of Mitterrand, who spent two days in Zaire before arriving here yesterday.

Mitterrand, besieged by domestic economic problems and recent diplomatic embarrassments that have pushed his popularity to an all-time low, had hoped to recoup somewhat at this summit, which in the past has been a showpiece of French influence and leadership in Africa.

The French president spent most of his 30-minute speech today discussing Africa's economic and food problems and proposing that the industrialized western nations increase their aid to Africa. But the Chadian issue has overshadowed other questions here despite French attempts to deflect criticism and downplay its significance.