Greece and France today signed an arms cooperation agreement that could lead to large Greek purchases of French weapons and possible coproduction of French aircraft here.

The accord, signed by Prime Minister Andreas Papandreou and French Defense Minister Charles Hernu is the first step toward the new Greek government's goal of making Greece less dependent on the United States for arms.

The signing of the agreement comes at a time of intense behind-the-scenes competition among U.S., French and other West European aerospace firms for the sale of fighter aircraft to the Greek Air Force. The Greek armed forces say they rely on the United States for about 80 percent of their weapons needs.

The agreement follows months of contacts between the Greek and French governments, launched promptly after the Greek Socialists swept to power in last October's election, seemingly on the same political wave that had earlier carried the Socialist Party to victory in France.

Hernu, who flew here from Paris for the ceremony, said the agreement reflects "the will of France to offer Greece an alternative against military dependence on any superpower," a reference to the Papandreou government's policy of diversifying Greece's arms sources away from the United States in order to pursue a more neutralist foreign policy.

The rhetoric, however, masks scrambling by France to beat other Western competitors to a contract for fighter planes to replace the Greek Air Force's aging F4C Phantoms. The Air Force is believed to be considering purchasing the French Mirage-2000, the American F16 and F18, and the West German-British-Italian Tornado.

Deputy Defense Minister George Petsos is scheduled to visit the United States in late May and the purchase of U.S. aircraft is thought to be high on his agenda.

A deciding factor in the Greek government's final choice, sources here said, will be the possibilities for coproduction. The idea is to expand the operation of the Hellenic Aerospace Industry, the showcase Greek arms industry operating at Tanagra, north of Athens, under a six-year contract with Lockheed Aircraft International.

Hellenic Aerospace has the technology to overhaul the older type of Mirage F1C aircraft but is mainly geared toward the maintenance of U.S.-made planes.