More than 200,000 Cambodian refugees who have fled a Vietnamese offensive against their resistance settlements along the Thai-Cambodian border in the last six months are turning their temporary "evacuation sites" in Thailand into semipermanent camps.

Assembled in a dozen such evacuation sites along the 450-mile border are about 225,000 Cambodian followers of three resistance groups battling the six-year-old Vietnamese occupation of Cambodia, and more than 3,500 Vietnamese "land people" who have fled their country overland across Cambodia.

The situation poses a dilemma for Thailand, which has no desire to harbor such a huge refugee population on its territory indefinitely, but feels it must continue to support the Cambodian resistance. Vietnamese forces in the past have pulled back from the border after annual offensives during the November-to-May dry season. But this year, they have dug into the resistance camps they have captured and announced their intention to prevent the refugees from returning to Cambodia.

Among the most desperate people in the camps are Vietnamese refugees like Danh Man, a resident of a crowded, fenced-off section of this evacuation site. The special section of a camp of 65,000 Cambodian refugees is reserved for Vietnamese "land people."

Six months ago Danh Man, 42, left Vietnam on a hazardous journey across war-ravaged Cambodia with his wife and 13-year-old daughter. Besides the risks, the trip cost him about $330, a small fortune in Vietnam.

For Man, a former interpreter for the U.S. Special Forces during the Vietnam War, the cost and the risks were worth his hopes of reaching the Thai border and entering the refugee pipeline for resettlement in the United States.

Today, those hopes look forlorn. Like about 3,500 other Vietnamese "land people" here who have fled their country overland across Cambodia, Man is in a bureaucratic limbo.

In a move to deter further arrivals, the Thai government has declared the land people ineligible for resettlement, and there is nowhere else to go.

Just across the border in western Cambodia are occupation troops of the Hanoi government, and here the refugees are jammed among potentially hostile Cambodians forced to flee their homes by those same Vietnamese troops.

"The future looks quite grim for them," a western relief official said.

Elsewhere at Site 2, about 40 miles north of the Thai town of Aranyaprathet and a couple of miles west of the Cambodian border, about 65,000 noncommunist Cambodian refugees are fixing up their bamboo-and-thatch homes and trying to improve drainage and sanitation facilities with the help of U.N. and other relief agencies.

Thirty miles south of Aranyaprathet, about 36,000 followers of the Communist Khmer Rouge are just starting to build more durable structures at a camp called Evacuation Site 8.

For the most part, the Khmer Rouge population remains encamped under makeshift shelters of U.N.-supplied blue plastic sheeting, poor protection from the monsoon rains.

According to western relief officials, Khmer Rouge leaders have been reluctant to give their site an air of permanence and are clearly unhappy to be on Thai soil.

However, some of their followers apparently do not share their feeling. Relief officials report that a loosening of Khmer Rouge control over the population since the move to Thai territory in February has led to signs of more relaxed social conditions, including an upsurge of wedding ceremonies and more openness toward foreigners.

While the refugees at Site 8 may move to another location on higher ground, most Cambodian refugees are expected to remain in the present evacuation site until the end of the year, and possibly indefinitely if the Vietnamese succeed in sealing off the Cambodian border.

Here at Site 2, officials of the Khmer People's National Liberation Front, the main noncommunist Cambodian resistance group, already have set up crude wood-and-thatch hospitals, with outpatient, pediatric and obstetric wards, dental clinics and administrative buildings. As part of the Thai policy of deterring more refugee arrivals, conditions of the Vietnamese land people are more squalid. After allowing the Vietnamese land refugees to be processed by other countries for resettlement abroad on two previous occasions -- in 1983 and earlier this year -- high authorities say the doors are now closed.

Yet the refugees continue to arrive. According to Danh Man, about 100 Vietnamese a month still make their way here.