An international conference agreed in principle today to turn a tiny Indonesian island into a processing center for Indochinese refugees bound for resettlement in the United States and elsewhere.

"If this system can be duplicated in other parts of the region we may develop a capacity that is sufficient to really make a very marked difference in alleviating the pressures" on the countries to which the refugees initially flee, said U.S. delegate Shepard C. Lowman.

More that 250,000 refugees are awaiting resettlement in Thailand and Malaysia. Those guaranteed permission to settle permanently in countries such as the United States, France and Australia would go to the Indonesian island and others selected as processing centers.

The island designated by Indonesia, Galang, is about 25 miles south of Singapore and would hold up to 10,000 refugees at a time. The Philippine delegation officially offered Tara island about 145 miles south of Manila as a second processing center.

The 24-nation conference on the refugees problem, the first attended by Vietnam, asked the United Nations High Commissioner for Reguees to conduct a feasibility study of the proposal to establish processing centers. Several delegates pointed out that a final decision was postponed by requesting a feasibility study.

The offer made by Vietnam Tuesday to release as many as 10,000 refugees a month directly to the United States and other countries was received with interest Wednesday by the State Department in Washington.

Charles Freeman, a State Dept. refugee officer, told reporters that the United State is awaiting a full report of the offer, which was made at the Jakarta conference.

"Obviously it's preferable if people feel the conditions are intolerable in Vietnam . . . for them to get out through some procedure which does not threaten their lives as the smallboat departures do. It's been estimated as many as 50 percent of the people who come out of Vietnam by boat don't make it" Freeman said.

[Refugees sent directly from Vietnam for resettlement elsewhere apparently would not go through the reprocessing centers discussed in Jakarta]

U.S. officials estimate that 20,000 people are leaving Vietnam each month by boat heading mainly for Malaysia and Thailand. At the same time, about 10,000 are leaving temporary camps in those two countries for permanent resettlement elsewhere.

Delegates at the Jakarta conference said privately that they had hoped to draw out the Vietnamese delegation on the question of how Hanoi is handling the ethnic Chinese who make up most of those fleeing the country. But Indonesian Foreign Minister Mochtar Kusumaatmaja, chairman of the conference, restricted discussion to the processing center.

"We came here to solve problems not to raise hell" he said.

Vietnamese Ambassador Vu Huong reiterated at the conference a pledge made earlier this year to cooperate with the United Nations High Commissioner on Refugees in a program of "orderly departure" for those wishing to leave Vietnam. His statement was publicly applauded by delegates as a means of stemming the tide of Indochinese risking their lives daily by fleeing in small boats.

Some delegates said outside the conference, however, that the Vietnamese proposal to send up to 10,000 refugees a month directly to the United States and elsewhere would put pressure on these countries to accelerate their intake of refugees. The United States is currently accepting 7,000 Indochinese refugees a month. Funds to resettle these refugees in the United States run out early next month unless Congress acts before then on an administration request for $100 million in supplemental appropriations.

While delegates argued in Jarkata over the wording of the final conference document, word was received from a refugee camp on another Indonesian island. Bintan, Of the suicide of a 72-year old man from Vietnam. He hanged himself because he, his wife and two daughters had not been accepted by any country for permanent settlement.

"We will have more of that, I am sure, if the rich countries go on dragging their feet," said an Asian delegate to the conference who did not wish to be identified.

In related development, Reuter reported from Bangkok:

About 12,000 refugees from Cambodia have crossed into Thailand in the past few days. Refugees said Vietnamese-led forces controlling the border were separating ethnic Chinese from the others and collecting the Chinese near a town 30 miles inside Cambodia.

Officials in Bangkok said an estimate 6,000 refugees who crossed the border into Thailand last Weekend were ethnic Chinese. They did not know if another 6,000 who crossed yesterday were also Chinese.

Diplomatic sources in Bangkok said the Vietnamese-led forces in Cambodia were not preventing the exodus and might be encouraging it, to judge by refugees accounts.