The flow of Vietnamese refugees to countries in Southeast Asia has dropped by an average of 20 percent this year, except in Indonesia where the refugee population is rising.

U.S. measures to deter new arrivals through more selective, slower screening procedures have not so far had the expected impact on refugee movement to Indonesia. As as result, immigration and international relief officials are speculating privately on what new measures can be taken to stem the refugee flow.

Indonesia's refugee burden is due in part to its geographical position as the last stop in the southward drift of refugee boats leaving Vietnam. To the extent that information travels back along the escape route from camps in Southeast Asia to Vietnam, organizers of illegal escapes know there is now no resettlement from Thailand's camps of boat people, that Singapore will not hold refugees longer than 90 days and that Malaysia has returned boatloads of refugees to the sea. The last remaining option then, is Indonesia.

The rising number of Vietnamese in the camps is also a result of six months' enforcement by the U.S. government of stringent immigration policies designed to distinguish between true refugees from political persecution and economic migrants seeking a better life.

Last April, because of a report written by U.S. refugee program workers saying that up to 80 percent of those interviewed did not qualify as refugees, the U.S. government revised its screening procedures to examine the circumstances and motivations of arrivals to the camps.

This change in procedures was reported to Vietnam over the Voice of America and British Broadcasting Corp. Under a directive from the State Department, Vietnamese arrivals to refugee camps after the cutoff date of May 1 without military or family connections to the United States are not presented to the U.S. immigration officers. Second, there is no longer an automatic assumption that all arrivals from Vietnam were refugees from persecution as defined under the Refugee Act of 1980.

A third policy change was to cease giving a higher priority to unaccompanied children who had been sent by their families to act as an "anchor" on U.S. soil for the remaining relatives. U.S. officials are now to apply the same criteria to the "anchor cases" as to adult refugees. A State Department official said recently there had been a slight decline in this kind of case and, as of November, there were only 100 minors not yet interviewed by international officials.

Although a few arrivals with very close connections still qualify for resettlement in the United States under normal immigrationprocedures, it was hoped that these adjustments in policy would be relayed by refugees in camps back to their relatives and friends at home.

With the evidence not yet all in, officials from the U.N. High Commissioner for Refugees are reluctant to pronounce the effort to stem the flow of refugees a failure. Many arrivals had already committed themselves to departure or were actually at sea when the announcement was broadcast, and a number of arrivals are farmers or fishermen.

"These people can hardly read or write and never listened to the VOA in their lives," said a U.N. officer.

The military government of Indonesia also wants to stave off a continuing flow of economic migrants from Vietnam. But the U.S. deterrence policy, with its more careful and inevitably slower screening, works against the immediate Indonesian plan to phase out the refugee program and adapt the existing camps--a large one on Galang Island and a small camp on an outlying island named Kuku--for military use.

Despite firm U.S. and U.N. commitments that all Vietnamese will be removed from Indonesia before the program is closed down, the Indonesians show anxiety that someone's mind will change and Indonesia will be left with a welfare burden it can ill afford.

Clearly tension is rising between the host government and the refugee program officials who provide them with statistics, assurances and voluntary aid.

In October, a delegation of Indonesians, including four generals, toured Galang, Indonesia's main refugee resettlement camp, on a verdant and isolated island as close to Singapore as it is to the main Indonesian island of Sumatra.

This camp, with a population of 13,294 at the end of October, is divided into three sites, one for Khmers bound for France, another for unscreened arrivals awaiting interviews with U.S., Australian, French and Canadian officials, and finally those guaranteed resettlement in the United States.

The very efficiency and apparent permanence of the camp sites, with their churches, schools, garden, roadside shops run by entrepreneurial refugees and even coffeeshop-discotheques run by refugee franchises, attest to the duration of the Vietnam refugee problem.

The Indonesian military touring the camp were clearly worried about why their camp's population caseload now averages 6,090 a month when a year ago it was 4,645. The military visitors collected their own information from the unreliable refugee grapevine, which did not always tally with official U.N. figures.

Of greatest concern to all is the increasing population of young males who are leaving Vietnam in ever larger numbers to evade service with Vietnamese troops occupying Cambodia.

Debate continues among diplomats and refugee organizations on what the next step should be and where the rejected refugees will go. Repatriation is raised and then rejected as a new policy, since Vietnam had made it clear it will not take the emigrants back.

The refugees, however, know of the pressure on the United States, Australia and other countries to take them all eventually.

To Australia, as well as the United States, bilateral relations with Indonesia are important. The contradiction between slowing down resettlement to deter refugees, and speeding it up to clear the camps for the Indonesians, is a paradox no one can immediately solve.