The French government has been thrown into disarray by the news of a major oil prospecting contract between the French national oil company and Libya, a report that coincided with Libya's announcement of its arms-backed merger with neighboring Chad.

From right to left, French editorialists denounced the oil exploration agreement, revealed yesterday. They said it gave the appearance of a payoff for French inaction against Libyan military assistance in the takeover three weeks ago of the capital of the former French colony.

The imbroglio within the French government underlined the ambiguity of Franco-Libyan relations. It has left diplomats of other Western countries expressing bewilderment over the real nature of the Paris-Tripoli relationship.

"Crass commercialism" was the only motive one professional observer said he could come up with to explain the risk France has taken of disillusioning its traditional friends and allies in French-speaking black Africa that they can count on French military protection.

There are also growing hints that President Valery Giscard d'Estaing of France may have some domestic political reasons for treading softly in his relations with the Libyan leader, Col. Muammar Qaddafi. The newspaper Le Monde noted today that Qaddafi has a great deal of inside information on the political affairs involving the French-deposed Central African emperor Jean-Bedel Bokassa and his complicated personal relations with Giscard.

Insiders know that there was a plan to transfer Bokassa from his present place of exile in Abidjan, Ivory Coast, to the Libyan capital of Tripoli, where he would have been unmuzzled. Those intimately involved say that Qaddafi withdrew his approval for the plan after a visit this fall to Libya by the French Foreign Ministry's African and Middle Eastern affairs director, Serge Boidevaix.

After a Cabinet meeting this morning, the French Industry Ministry issued a communique in the name of the French government saying that ELF-Aquitaine, the national oil company supposedly under the ministry's authority, had acted without consulting the government on the "timeliness" of the accords and said that the ministry "had not given its approval."

Ministry officials said it was "open warfare" between Industry Minister Andre Giraud and ELF-Aquitaine President Albin Chalandon, a prominent old Gaullist and former industry minister. Chalandon went to Libya in late November to negotiate the oil prospecting agreements.

An ELF-Aquitaine spokesman said the accords were signed Dec. 4, when, it is now known, the Libyans were already transporting their tanks across the Sahara for the assault on the Chadian capital of Ndjamena. It fell Dec. 15 after months of civil war that the Libyan intervention was decisive in ending.

The Libyan oil company countersigned the accords, the ELF-Aquitaine spokesman said, "in the final days of December" -- after it had been clearly established that France would not carry out its threats to counteract Libya.

Some observers speculated that Chalandon will lose his job. But Chalandon let it be known he will not let himself be made the scapegoat, saying he went to Libya "with the agreement of the public authorities on the public level" -- an apparent reference to Giscard himself.

The dispute creates a major political delemma for Giscard in an election year. Gaullist party leadership, theoretically part of the government coalition, is increasingly openly working for the president's defeat in the May elections.

Observers questioned whether the president can afford to dismiss one of the few leading Gaullists still associated with the government. But if he does not do so, he opens himself up with renewed force to the already widespread charge of accepting Quaddafi's oil payoff in exchange for granting the Libyan leader a free hand in Chad.

Yesterday, before the internal French government dispute broke into the open, the Foreign Ministry spokesman said: "France disapproves of the Libyan action in Chad and opposes Libyan intervention in Chad. But France's hostility to Libya's African policy is no reason to stop French oil companies from prospecting there, just as American and British companies do." Robert Galley, another old Gaullist who recently was made defense minister in addition to keeping his job as African cooperation minister, apparently because there are not enough Gaullists to go around in the cabinet, went on television tonight to respond to the groundswell of criticism. He said he could not see what a French military intervention in the Chad civil war could have achieved, and he recalled that there was heavy public pressure last year for France to withdraw its peacekeeping forces from Chad.