The Thai government Monday will begin repatriating Cambodian refugees who agree to return to their war-torn country.

Thai officials and members of the United Nations High Commission for Refugees (UNHCR) today stressed that the repatriations -- which could involve about 160,000 refugees at two camps -- will be voluntary. But relief workers and some refugees at the camps fear Cambodians may be coerced into returning to the homeland they have fled.

In 1979, the Thai government forcibly repatriated more than 40,000 Cambodians, many of whom died. The incident drew strong international criticism.

The Cambodian Foreign Ministry warned yesterday that the repatriation would "threaten the stability of the region." The statement, carried by Phnom Penh Radio was monitored in Bangkok.

U.S. State Department officials said yesterday that the program appears to be a reasonable response to the legitimate desires of some Cambodians. But they added that because of the high degree of concern, international observers will closely monitor the program.

[Richard C. Holbrooke, assistant secretary of state for East Asian and Pacific affairs, yesterday said, "We are concerned that any repatriation be truly voluntary. . . There are a lot of questions that we are looking at and trying to get answers to."]

The repatriation is scheduled to begin Monday at this huge camp near the Cambodian border. U.N. officials and Thai military officers first will interview the refugees to determine if they are returning voluntarily. Refugees will be asked to sign written statements saying they are returning of thier own volition.

On Wednesday, the program is to begin at the Sakeo Camp, 30 miles away. Relief workers there fear pressure is being exerted by Cambodian backers of former premier Pol Pot who entered Thailand among the refugees.

A Thai sound truck has been traveling among the thatched huts at Kao-I-Dung announcing the repatriation program to the refugees.

Although the Cambodian-language announcements stressed that the move is voluntary, they also said the alternative -- resettlement in another country -- is "just a dream."

In a camp alive with rumors, some refugees appeared frightened and upset, convinced they would be forced to go home. Others were confident the move would be voluntary.

One Cambodian-speaking relief official who is often in Sakeo said he was "extremely worried" that many people there will be forced by their own leaders to return. He estimated that there are fewer than 500 hardcore supporters of Pol Pot among the 160,000 refugees, but said these might intimidate thousands more into returning with them.

He said these strongmen have been telling the refugees that U.N. involvment in the repatriation program means their war-torn country is safe and at peace.

He said he believed the repatriation is truly intended by its organizers to be voluntary. But, he said, at night "nobody is at Sakeo to protect the people, so they'll just have to go along with what the [Pol Pot] Khmer Rouge tell them."

Another relief official said, "We're afraid that once the repatriation gets its own momentum and the Thai troops are running the show, there may be a tendency for things to just run away. Some Thai soldiers may say, 'We've gotten the first thousand back to Cambodia, why don't we see how many more we can get?'"

Several months ago, UNHCR officials tried to initiate a program to repatriate refugees to their villages, but negotiations with the Cambodian government broke down.

Thai officials decided to begin their own repatriation program, and since the UNHCR cannot oppose voluntary departures, a joint decision was made to organize refugees who want to return to Cambodia, and to take them to the border.

Relief officials fear, that the refugees will not be able to get from the border to their villages because of continued fighting between Cambodian government troops and anti-government forces.

"There is no question that most [of the returnees] are just going to the border and just going to hunker down there," one relief official said.

Some 600,000 Cambodians are already living along the 500-mile Thai-Cambodian border, most of them in makeshift, sprawling settlements that receive food from international agencies.