Vietnam agreed today to consider setting up centers on its territory to process departing refugees and regulate the uncontrolled flood of "boat people" it has allegedly expelled into the South China Sea.

The vietnamese offer was seen here as potentially the first step in a deal to solve the problems created by more than 350,000 Indochinese refugees.

Opening a two-day conference on the refugee problem, U.N. Secretary General Kurt Waldheim appealed to delegates fro 57 particpating countries to set up a program of action that would save the lives of thousands awaiting permanent resettlement in Indonesia, Malaysia, the Philippines, Singapore, Thailand and Hong Kong.

While a number of Western delegates expressed concern that the Vietnamese refugee centers might be turned into concentration camps, they nevertheless seemed encouraged that Vietnam is starting to recognize that it cannot simply push it undesirables into the sea.

A major breakthrough in American efforts to get various countries to provide holding centers on islands came when the Philippines pledged an island to shelter 50,000 boat people temporarily.The Philippines announcement was greeted by the only applause of the opening day of the U.N. sponsored conference at the Palais des Nations, the headquarters of the old League of Nations.

The real work of the conference was going on in dozens of huddles in small conference rooms honeycombed throughout the building, with American delegates dispersed in negotiation with other delegations. One of the major American efforts was understood to be getting Indonesia to match the Philippines' contribution.

The head of the hug 140-member U.S. delegation, Vice President Walter Mondale, did not appear on the conference floor today, but spent the day closeted in successive meetings with the heads of the Japanese, British, Chinese, French and Canadian delegations. Subordinates met with the Vietnamese.

The Americans were caught off guard by President Carter's impromptu announcement last night in Washington that he was sending the U.S. 7th Fleet to pick up refugees at sa. U.S. delegates said they had had no advance word of the presidential move and were trying to figure out how to weave it into Mondale's speech Saturday.

Representatives of the U.N. High Commissioner for Refugees were particularly pleased that they appeared to be getting close to their objective of getting pledges of permanent resettlement for 250,000 of the more than 350,000 Indochinese refugees provided intermediate holding camps could be found for them immediately along the lines of the Philippines' offer.

But Deputy U.N. High Comissioner Dale De Haan, formerly Sen. Edward Kennedy's staff refugee specialist, expressed concern in an interview that the pledges must be made automatically renewable for more refugees, or there will be another similar crisis in six months with still another conference needed.

The contries of the Association of Southeast Asian Nations, which has borne the brrunt of the Indochinese refugee outflow, took a tough united stand that was summed up by Malaysian delegate Mohammed Ghazail Shafie in the formula, "There can be no first Asylum without fainal asylum."

The Malaysian said that his country's pusing of Vietnamese refugees back out to sea was somethiing "we ourselves do not relish and find distasteful" and amounts to "a measure of the desperate situation we are in."

U.S. sources said that one of their delegation's primary objectives was to reassure the Southeast Asians of Western support and sympathy. The sources said they felt that the package of increased Western aid and resettlement pledges tht has been gradually building up since the Tokyo summit has veen sufficiently impressive to reassure the ASEAN countries.

Another American concern, a U.S. source said, was "to put some heat on the Vietnamese, but they are not wilting very much yet."

The Americans said that a French proposal here today that there be a six-month "moratorium" on the departure of more Vietnamese refugees may be what takes place in practice if the Vietnamese conclude that the pressure of international opinion against them is too heavy.

The French moratorium proposal, couched in terms conciliatory to Vietnam, nevertheless clearly implied that the Vietnamese government has the power to stop the refugee outflow.

U.N. sources said privately that this is also their view. They noted that in the last fedw weeks preceding the conference, the number of boat people has fallen off sharply.

The U.N. sources do not lay exclusive blame on Vietnam, however, saying that China and even the United States have done things that have incited refugee departures. In the case of the United States, the sources point to alleged broadcasts by the Voice of America telling potential refugees how to go about leaving the country. The sources said that payments to the Vietnamese to get ethnic Chinese out of Vietnam can be traced through bank transfers by Chinese syndicates in San Francisco and Hong Kong.

The phrase "orderly departure" reappeared often in practically all of today's speeches, including those of the feuding Vietnamese and Chinese.

But the Vietnamese conception of "orderly departure" may differ sharply from the Western one.

"The laws of the Socialist Republic of Vietnam." said Vietnamese delegation chief Phan Hien, "include stipulations that allow for the severe punishment of clandestine departures."

The United States will not pay for anything that smacks of "concentration camps" in Vietnam, said a U.S. delegation member.

French Foreign Misinster Jean Francois-Poncet said at a press conference that he had made a deliberately lowkey presentation designed to enlist Vietnamese cooperation.

Other delegations did not try to spare the feelings of the Vietnamese, however. Chinese Deputy Foreign Minister Zhang Wenjin spoke of Vietnam a a "millitary dictatorship" that is guilty of "military dictatorship" that is guilty of "militarism," "expansionism," "genocide" and anti-Chinese racism.

British Foreign Secretary Lord Carington said that Vietnamese policies must be blamed for the flight of the boat people. In a press conference later, he spoke of the danger of transit centers in Vietnam turning into concentration camps."

Britain pledged to accept 10,000 more refugees and $10 million to deal with the problem. He french pledged to take 5,000 more, in addition to an earlier pledge of 5,000.

Canada pledged the biggest effort today -- 42,000 more refugees on a matching basis between the federal government on one side and local governments and private groups on the other. for example, the city of Ottawa has pledged to sponsor 4,000 refugees and Vancouver 5,000. The Canadian federal government agreed to finance a like number in each case.

China pledged to resettle 10,000, and, for the first time, offered a contribution -- $1 million -- for U.n. refugee work.

Disappointment was expressed in the corridors, however, with the efforts of such countries as West Germany (10,000 refugees all told), Sweden (750 more) and Brazil, which pleaded that it has is own internal resettlement problems to deal with already.

Nevertheless, U.N. officials said that they had counted up pledges of permanent homes for 233,000 refugees by the end of the day. About a fifth of the pledges were brand new.

Originally billed as a conference on the problems of all Indochinese refugees, the meeting was largely reduced to dealing directly with the Vietnamese problem only.

Cambodian was not invited because

The cambodian was not invited because the United Nations did not know which of the two Cambodians governments to invite. When the permanent Cambodian delegate in Geneva, who represents the Pol Pot government, tried to give a press conference in the Palais des Nations yesterday, the Vietnamese served notice that they would boycott the conference if he spoke on the premises. CAPTION: Picture, U.N. Secretary General Kurt Waldheim (right) opens the refugee conference with high Commissioner Poul Harting.