The 11th Olympic Congress opened today in the lush green setting of this stylish West German resort town, a tranquil backdrop that belied the controversies and tensions within the international Olympic movement.

Always the professional diplomat, Juan-Antonio Samaranch of Spain, the president of the International Olympic Committee (IOC), stressed the unity of the Olympic movement in a keynote address. But he couldn't overlook the discordant themes of racial discrimination, eligibility rules, a permanent Olympic site and performance drugs that are expected to dominate this week-long session that, coming every eight years, serves as a sort of summit meeting of world sports groups.

For the moment, the threat of a motion here by black Africans and the Soviets to move the 1984 Summer Games from Los Angeles in protest over the American tour of the South African rugby team, the Springboks, appears to have been averted.

In any event, a motion to move the Games would have little chance of passing, according to officials.

Moreover, the Soviets are widely believed here to be unprepared to back out of the Los Angeles Olympics, since it would mean giving up one of their prime propaganda tools -- winning lots of medals.

Black African sports officials, meanwhile, appear to have been persuaded that both the IOC and U.S. Olympic officials did all they could to block the South Africans' tour and, particularly in view of the fact that rugby is not even an Olympic sport, should not be held accountable.

But the black Africans can be counted on to use the congress as a platform to denounce racial discrimination, including what is anticipated to be a militant speech Friday by Jean-Claude Ganga of the Congo, the former general secretary of the Supreme Council for Sport in Africa.

Calling apartheid in sport "a difficult and tricky problem," Samaranch today noted that the IOC took a firm stand on the matter by being the first to ban South Africa in 1970 on grounds of violating the Olympic charter.

"All of us here are resolutely and definitely opposed to this scourge of our world," Samaranch declared. "We intend to continue our struggle without respite until this notion and its consequences have disappeared completely."

The congress is not empowered to make any decisions affecting the Olympic Games. Its purpose is consultative, allowing the national committees, sports federations and athletes and coaches a chance to offer suggestions to the IOC.

Whether the conference will help to knit or deepen the rifts that exist between Olympic planning groups is the challenge confronting the 600 delegates from 147 countries who are to trade opinions in a minimum of 108 scheduled speeches and at a reported cost of $3.1 million.

"This congress provides an opportunity to look at the total movement," said F. Don Miller, executive director of the U.S. Olympic Committee. "The principal thing is it provides for an exchange of ideas."

Even before things got officially under way today, however, U.S. officials complained about being excluded from the schedule of primary speakers. Mario Vazquez Rana of Mexico, the president of the Association of National Olympic Committees, explained somewhat lamely that the omission occurred because the new head of the American Olympic Committee, former Treasury Secretary William Simon, had not been chosen at the time the selection of speakers was formally submitted.

The Americans may not have been denied much, however, since the more or less preprogrammed nature of the debate results in rather sterile sessions. Most of the important discussions take place informally outside the meeting rooms.

Signaling one Olympic breakthrough, Samaranch disclosed that the IOC's executive committee plans to propose several women as members of the committee, thus ending an 87-year history of all-male membership.

Most likely to be the first woman is a 29-year-old Finnish sports teacher, Pirjo Haeggman, who has been suggested by the outgoing Finnish member of the IOC, Paavo Honkajuuri, to take his seat. Haeggman is six months pregnant, a fact that has compounded the old guard's consternation at the change.

On other points, a delegation of 36 medal-winning athletes invited to the Congress will be pressing for liberalization of the amateur-status rule, arguing that athletes should be allowed to capitalize on their fame or receive pay for sports other than their Olympic specialties.

As a mirror, too, of the north-south and east-west political disputes that occupy other international arenas, Olympic groups from the developing world and Communist-bloc countries will be renewing calls for greater democratization of the IOC.