Soviet President Leonid Brezhnev today ended a three-day visit to France that has served as a sounding board for his concern over the troubled state of American-Soviet Relations.

Repeatedly in his talks with French President Valery Giscard d'Estaing this week, Brezhnev seemed to beam his message toward Washington as much as toward his French audience here. The Carter administration was, in effect, a silent partner in the French-Soviet summit talks.

Hovering at the edge of the Soviet effort to intensify dialogue with France has been an unspoken question that clearly preoccupies the Soviet leader: What would detente look like and be worth without the Americans?

Brezhnev, who reportedly read most of his remarks to Giscard but interspersed them with long digressions, set the tone of the meeting in the first encounter at the Rambouillet chateau Monday afternoon when he talked for 2 1/4 hours of the three-hour meeting.

As he told Giscard that detente "is the only practical approach to avoid a [WORD ILLEGIBLE] in this nuclear age," Brezhnev suddenly stopped and asked the French leader who in the delegation was "in charge of propaganda."

When the delegation spokesman was pointed out, Brezhnev asked him to be sure to tell reporters and the public exactly what he had said on this point.

Soviet and French spokesman provided far more detailed accounts of the meeting than is usually the case here, including precise quotations.

Publicly warning during a dinner toast last night that a renewed arms race could wreck "the fine words and declarations of attachment to peace," Brezhnev privately told Giscard today at their final talk that he is deeply concerned by the continuing failure of the Americans and the Soviets to reach agreement on strategic-arms limitations.

French officials were authorized to convey this, and an earlier Brezhnev assessment that no progress had been made in recent U.S.-Soviet meetings on strategic arms, to reporters.

The two leaders signed a joint declaration and separate statements on detente and nuclear proliferation before Brezhnev returned to Moscow late this afternoon.

The documents added little to previously stated positions, but Giscard echoed Brezhnev's private concern by saying that their joint call for "intensified" efforts for detente was important because "It comes at a time when doubts is being expressed around the world as the very concept" of detente.

The bitter U.S.-Soviet quarrel on human rights also was evoked by the documents. The Soviets did accept a French-initiated mention in the declaration on detente of the importance of "respect for human rights and fundamental liberties by all states," but Giscard specified later that France does not believe in raising "particular cases" of abuses of human rights with other governments.

He made no mention of the Carter administration's support for specific Soviet dissidents, but his intended contrast was clear.

Giscard failed to get any specific mention of his desire for a lessening of "ideological competition" as a condition for detente into the final declarations. This point appeared to have deeply irritated Brezhnev during their last meeting in 1975, but he did not react to it when Giscard mentioned it yesterday in a private session.

The French gave only a faint endorsement of a Soviet proposal for a global disarmament conference, and Brezhnev made it clear in public remarks that France's continuing refusal to join any disarmament talks was the main point of contention between them during the visit.

There joint call for resumption of the Geneva Middle East peace talks before the end of the year stood out in the positions they stated on other international issues.

"Representatives of the Palestinian people" should be at the conference, they said, and the two countries supported Palestinian rights "including the right to have a country," as well as the right "of all states in the region, including Israel" to an independent existence.

In recent months the Soviet Union has begun publicly citing Israel as one of the countries of the Middle East that have a right to "reconized and secure" frontiers.

A declaration of Franco-Soviet trade called for tripling the current trade level and extended the two nations' economic-cooperation agreement to 10-years, including more joint industrial projects. There were also agreements on research projects in transportation and environmentally safe industrial plants.