The president of the International Olympic Committee, Juan Antonio Samaranch, said today he had received assurances that Soviet Bloc states would participate in the 1988 Summer Olympics even though they do not maintain diplomatic ties with host country South Korea.

He told reporters attending the 90th IOC session here that East Germany's head of state, Erich Honecker, and sports minister, Manfred Ewald, informed him that the Soviet Bloc countries are eager and willing to attend the Games. But Samaranch warned, "If the political situation becomes as tough and as complicated as in early 1984," the possibility of another walkout could not be ruled out.

"Boycotts always occur for political reasons," he said. "If everything is normal, then I am sure that everybody will participate. Maybe we will have problems again, but we are getting used to it."

Earlier in the week, South Korea's sports minister, Young Ho Lee, said signals he received here from East German and Bulgarian delegations convinced him that the Seoul Games would "be the first Olympics in 16 years free of any organized boycott."

The Soviet Union and 14 other communist countries skipped the 1984 Games in Los Angeles, ostensibly because of lax security precautions for Soviet Bloc athletes.

In 1980, the United States led a Western boycott of the Moscow Olympics in protest of the Soviet invasion of Afghanistan. Four years earlier, many African nations spurned the Montreal Games over a New Zealand rugby team's tour of South Africa.

The prospect of another boycott in 1988 loomed when Moscow expressed serious reservations about the choice of Seoul as the site for the Summer Games.

But at the IOC meeting this week, the Soviet Bloc delegations have given positive signals about the 1988 Olympics despite the adamant opposition of ally North Korea.

The Warsaw Pact countries appear to be making strong efforts to reassure their own athletes and publics that their national teams will be represented in the Games.

Last year's boycott disillusioned many Soviet Bloc athletes, their relatives and fans . Western diplomats here have speculated that another walkout could bring domestic political repercussions, particularly in East Germany, where the quest for world honors in swimming and track events has become obsessive.

The Soviet Union and its allies are believed to have rebuffed North Korea during a meeting of top sports officials from socialist countries in Prague last October.

At that meeting, the East German and Czech sports ministers, backed by their Soviet counterpart, strongly resisted North Korea's call for socialist solidarity and emphasized the determination of their national teams to go to Seoul, according to diplomats in East Berlin.

A subsequent encounter here between East German and North Korean foreign ministers failed to bridge the positions, the diplomats said.

Although there is lingering concern that socialist countries could withdraw, Soviet Bloc analysts feel the domestic yearning to participate in the Olympics is so strong that the Soviet Union and its allies will need an overwhelming rationale to back out.

In his press conference today, Samaranch reported that Seoul and Calgary, Alberta, which will be the site of the Winter Games, were making good progress in arranging playing facilities and accommodations for athletes and spectators.

He said an important task of the IOC board will be to clarify the rules regarding amateur status.

He insisted that advertising would "be kept off the playing field" in future Olympics. "These are the only important sports games in the world where no advertising signs are posted in the stadiums and it should remain that way," he said.

He rebutted the claim that the Olympics are becoming too expensive to operate and thus nullify the chances of many countries that would like to be hosts of the Games. "We already have 12 cities seeking to get the 1992 Olympics, more than any previous number of requests," he stressed. "That shows more cities are interested than ever before in running the Olympics."

The IOC announced today that five persons, including Robert Helmick, president of the U.S. Olympic Committee and the International Swimming Federation, will be added to its 89-member board and that a major restructuring of the organization would take place in the wake of the resignation Wednesday of Monique Berlioux, the once-powerful director who lost a bitter power struggle to Samaranch.

He said a special commission would explore "how to run the IOC in the best possible manner" and would make public its recommendations next year.

As for Berlioux, who sat in stony silence next to him on the podium, Samaranch duly noted that the IOC "recognized her valuable contributions to the Olympic movement" over many years, but "life must go on."