The report spread through Thailand quickly early this week, seeming to confirm the Thais' worst fears that the war in Camboida was spilling into their territory.

Three hundred Cambodians, most of them wounded soliders, were streaming across the border seeking safety and medical treatment, according to the report, and Thais braced themselves for a new wave of refugees.

But reporters speeding up and down the Thai side of the border found nothing but lonely Thai soliders and local militiamen who said they had seen no one pass by in days.

The apparently false scare underscored one of the many mysteries of the war in Camboida. It is producing very few refugees. So far it has been not a wave but a trickle.

"Mystifying," says one well-informed source here who keeps up with daily battle reports on the war between Vietnamese troops and remnants of the Khmer Rouge army. "It is surprising that so few have shown up."

The Bangkok office of the United High Commission for Refugees was preparing to assist up to 50,000 of the displaced Cambodians. The Thai government was considering transforming part of the former U.S. military base at Utapao into a gigantic refugee camp.

By the latest U.N. count, however, only about 200 uprooted Cambodians have come across the long Thai-Cambodian border and they have been accommodated in military compounds and police stations near the frontier. They are a mixture of soliders and civilians, the largest group being a band of 45 men who said they were farmers but who the Thais suspect had been soldiers.

More typical was the group of 14 men and women and one boy who came over near the Thai border town of Aranyaprathet this week. They said they were peasants and blacksmiths who fled when fighting erupted in northwestern Cambodia.

Last week, several hundred former officials and cadre of the dislodged Pol Pot government were reported gathered across the bridge from Aranyaprathet, trying to negotiate their escape route and bargaining with Thai officials. They never came across and no longer are believed to be in the vicinity.

A number of theories are advanced to explain the absence of refugees, but no one here really seems to know what has happened to the thousands who fled as Vietnamese tanks rumbled through.

It is assumed that the Khmer Rouge soldiers have regrouped successfully in many areas and have stayed to fight a guerrilla war. There are rumors that any who try to flee to the safety of Thailand are in danger of being shot by their own comrades.

Vietnamese tactics near the border have given the Khmer Rouge soldiers some breathing room. The invaders so far have been careful not to push all the way to the Thai border. They easily could have taken the vacated border town of Poipet this week, but their tanks stopped short and turned instead to the north and south. Thai Prime Minister Kriangsak Chamanand publicly warned the Vietnamese not to approach the border and apparently the advice has been heeded.

The effect is to give the Cambodian soldiers a narrow strip of untouched terrain on their side of the border and they apparently are using it to regroup in guerrilla units.

The absence of civilian refugees is even more puzzling. Thousands who were uprooted from their homes apparently are melting into the countryside. One theory is that they prefer to wait and see what the new government of Cambodia is like, since they suffered enough under the brutal regimentation of the Pol Pot leader-ship.

"A lot of them probably think that whatever comes now cannot be any worse than the last one," said one source. "Or maybe it's just that they don't know which way to go."

Thailand already is a haven for refugees of many political persuasions -- men, women and children who have fled a succession of wars and guerrilla battles in Indochina. There are Cambodian refugees who fled when the Khmer Rouge toppled the American-supported dictatorship of Lon Nol in 1975. Now there are about 200 who fled the fighting that unseated Pol Pot.

To complicate things further, about 80 soliders still loyal to Lon Nol emerged from mountain refugees into Thailand this week, having waged a three-year guerrilla war against a government that now has been toppled by the Vietnamese-backed Cambodian insurgents.

The U.N. refugee office here estimates that mearly 140,000 refugees of different nationalities are now in Thailand. Most -- about 120,000 -- are Laotians who fled the Communist takeover in their country. There are takeover in their country. There are an estimated 15,000 Cambodians uprooted by various struggles and nearly 5,000 Vietnamese who either came by boat from Vietnam or on foot from Laos.

All are in Thai-administered camps where they receive food, medical care and schooling provided by U.N. funds.