This remote corner of rural Thailand is scheduled to become the next "liberated area" of Southeast Asia.

The Communist Party of Thailand says it will liberate Labansal within six months.

Last month, guerrillas of the Communist Thai People's Liberation Army entered two villages in this district in daylight. They rounded up 109 civilians and marched them across the Cambodian border, 15 miles away.

In the past four months there have been many such raids and hostile incidents along the Thai-Cambodian border, according to Thai First Army headquarters. More than 1,000 persons have disappeared from their villages since the beginning of the year.

Here in Lahansai, at the forward operations base of the Thai army in this strategic sector, battalion Task Force 233 is hunkered down behind sandbags.

Until recently, troops were deployed to provide security for civil engineers pushing a road along the border. The road was planned to enable quick reinforcement of isolated villages, but Communist mining, sniping and harassing raids brought construction to a halt 12 miles short of the intended length. The security troops were withdrawn.

The battalion commander's briefing map showed a formidable line of five Thai insurgent bases facing his position from just across the border in their Cambodian sanctuary.

"We expect the next attack here," the commander said, tapping his finger against a grid square.

But his map showed no counteroperations by his own forces: No interdicting sweeps, no ambush patrols, no listening posts.

"It's difficult to get permission from higher headquarters for operations," the commander said. He adked that his name not be used.

Recently Thai security forces had a rare break. They arrested two guerrillas and six mored defected.

Daeng Kaeosri, 36, one of these guerrillas, claimed the Communists implicated him in their operations gradually, so that he was hardly aware of being drawn in.

"The first time, two men came to my farm house," he said. "They were unarmed. They asked me to buy a few things, some fish sauce and cigarettes for them. They gave me 100 baht [about $5] and said I could keep the change. The things I bought them came to 36 baht 50 satang."

Pornachai Paengphet, 16, another of the guerrillas, said he was in his father's paddy field when 15 guerrillas appeared and rounded up everybody in the hamlet, 24 persons.

"We all marched for three days through the forest in Lahansai before we crossed into Cambodia," he said. "We met two other Communist squads. They fed us sardines and rice and they took over guarding us. In the three days we never saw any Thai Army or police."

Phromma Wongninyong, 32, another guerrilla, said he was taken by guerrillas from a hillside where he was farming. He said he did not cross the border until four days later, when he was put into a group of 152 other abductees and recruits.

"I was sent to camp 54 in Cambodia," he said. "On the first day there was an opening ceremony with red flags and big pictures of Marx, lenin, Engels, Stalin and Mao. We had a meal with chicken, but that was the only day we got it.

"We had three instructors for political and military training. They introduced themselves as former university students who had come to the liberated area after the October riots two years ago. [In 1976 a battle between campus demonstrators and security forces in Bangkok led to the imposition of military government.] Our instructors were very gentle and very modest. They took us on training maneuvers in the forest. At night and on Sundays we had study and self criticism meetings. We were issued weapons, but not ammunition. We practiced dry firing, because we were told the rule was one round, one enemy life. And we threw dummt grenades.

"Our instructors said our struggle was being supported by the international communist movement, especially by Cambodia, China and Laos. They never mentioned Vietnam or Russia."

After one month Phromma was selected for assignment to a guerrilla unit back in Lahansai. he was issued a pair of olive drab Chinese army fatigue trousers, a black shirt and 120 rounds for his Soviet-bloc CKC carbine.

Before recrossing the border with seven other new guerrilla recruits and four veterans, Phromma was told that his mission was to liberat Lahansai. When he found himself back in the woods of his home district, however, he lost heart and crept away to give himself up.

There are residents of Lahansai who take heart from the periodic defections from the ranks of recent Communist recruits. A group of merchants and landowners have organized a village development program to encourage self-decense. The program includes lectures in anticommunism.

The businessmen have also renovated a decrepit World War II Japanese ambulance, donated medicine and offered credit and land to farmers willing ro tend fields close to the Cambodian border.

"This is good land; we have to help people," said Serm Noiuthai, 45, who returned after college in California to become the largest landholder in Lahansai.

"We are the people who will have leave if our land falls," another landholder said. "But we don't want to become refugees, so we must fight for our country."