MANCHING, WEST GERMANY, SEPT. 24 -- France and West Germany took another step toward closer military cooperation today when the leaders of both countries announced plans to establish a bilateral defense council to oversee a wide range of joint security efforts.

French President Francois Mitterrand disclosed the plans at a news conference with West German Chancellor Helmut Kohl after they observed the final day of a combined military field exercise that involved 75,000 troops and was unprecedented in size.

These maneuvers in southern Germany, 80 miles from the Czech border, marked the first time in 22 years that a large number of French troops have operated deep inside West German territory.

The planned defense council and the maneuvers are the latest in a series of steps over the past year to work more closely on security issues. Their long-term goal is to bolster Western Europe's ability to defend itself and thereby reduce its dependence on the United States.

A close Franco-German relationship is crucial to this effort because it provides a way for France to contribute to allied defense outside the military structure of the North Atlantic Treaty Organization. France withdrew from NATO's integrated military command in 1966, although it remains a member of the alliance's political wing. The two countries have the largest armies and air forces among U.S. allies in Western Europe.

"We have made a declaration of intent" to establish the defense council, Mitterrand said. Its purpose will be "to coordinate decisions and harmonize policies" on security, defense, research and armaments, he said.

A senior West German official said the council was expected to serve as an umbrella organization for three existing bilateral committees on military operations, logistics and procurement.

The two countries hope to set up the council by January, when they will celebrate the 25th anniversary of the Elysee Treaty that normalized the relationship between France and West Germany after World War II, the official said.

The official said the upsurge in Franco-German cooperation was a result of two factors: increasing calls in the United States for cutbacks in its troops in Europe and Europeans' unease over President Reagan's willingness to pursue what was perceived here as unrealistic disarmament goals at his meeting last year with Soviet leader Mikhail Gorbachev.

Acknowledging that Washington viewed the Franco-German cooperation with some concern because of the fear that it could weaken Bonn's commitment to NATO, the official said, "The Americans are always asking us to do more for ourselves. Now we are doing something, {but} now they have some distrust.

"They should be happy. Strengthening Europe's defense is strengthening western defense."

The importance that Kohl attaches to cooperation with France was evident in his decision to make the high-profile visit with Mitterrand to the maneuvers here after having made no such trip to a major NATO exercise earlier this month in northern Germany. These four-day maneuvers, named "Cheeky Sparrow," illustrate France's willingness to deploy troops deep inside West German territory to help defend against a Warsaw Pact attack.

West Germany and the rest of NATO have long been frustrated by France's insistence on keeping the three divisions that it has stationed in West Germany on the western side of the country, just across the Rhine River from France. NATO would like to have the troops available closer to West Germany's eastern border, to help repel a Warsaw Pact invasion as quickly as possible.

France temporarily placed 20,000 of its soldiers under West German command to help 55,000 German troops stave off an "invasion" by the "enemy" forces of "Redland." The participating French troops were part of France's Rapid Action Force established in 1983.

Mitterrand strongly reaffirmed France's policy of remaining outside of NATO's military structure but also emphasized that West Germany could count on French support in a crisis.

"Whatever the subtleties of language, whatever the strategies, France considers it her duty to come to the aid of her allies," Mitterrand said.

Kohl called the exercise "an impressive example of the close cooperation between the two states, which has reached an intensity that never before has existed."