"One day two of the girls tried to escape. But the adults who watched over us caught them and sold them to another factory. We never saw them again."

While her eyes darted about the floor and her speech was hesitant, Tongpun Panuram, 14, recounted working, eating and sleeping behind the locked doors of a rundown weaving plant south of here.

Recruited from impoverished families upcountry, children like Tongpun are called "the slave workers" in Thai newspapers.

They account for only a tiny fraction of Thialand's work force of 21 million, but their presence in back-alley establishments in Bangkok underlines the harsh disparities in wealth between Thialand's cities and countryside. The "slave" trade also allows factory and brothel owners to use for their own purposes the ignorant hopes or desperation of country parents.

Tongpun was among 15 girls freed las month by a police raid. She told her story last week at a government girl's home where she had lived while awaiting for her parents to be notified. Her father, a nearly illiterate farmer from Buriram Province on Thialand's arid northeastern plateau, listened in morose silence before taking her home.

"We got up at 5 a.m. then worked the looms from 8 until noon," Tongpun said. "After lunch we worked from 1 until 6. Then they gave us supper and let us take baths and we worked again until 10 p.m. At night they kept us inside."

In the last 18 months, Bangkok police have raided at least seven factories like Tongpun's and freed more than 140 children, as young as 10 years old. Some were sick and partically crippled from long hours in poorly lit and ventilated factory halls, where their work included making batteries, wrapping candy and sewing cheap shirts. Among others, who have not been lucky enough to be rescued, there are reports of deaths.

Labor Department officials say they are doing their best to stop this exploitation of minors, which is illegal under Thia labor laws. Still, many sweatshops continue to operate, with one department official quoted as estimating that as many as 5,000 children under 12 are employed illegally at factories.

"Who can say precisely how many children there are?" a social worker said, shaking his head in exasperation. "I only know the number is very high."

As in most developing countries, Thai children begin working at an early age. In the villages, where most Thias live, they help their parents with farmwork. In the larger towns they wash dishes, shine shoes, or sell newspapers to commuters backed up at traffic lights.

Earlier this month, however, U.N. human rights investigators in Geneva heard renewed allegations of outright sales of 500 children a week at Bangkok's Hua Lampong rail station. Tim Bond, of the London-based Minority Rights Group, testified that he had brought two boys, aged 12 and 13, for $35 each. He returned them to their parents, he said.

Similar allegations from the Antislavery Society, also headquartered in London, were published in mass circulatin newspapers here. Some labor specialists here believe that although the accounts are inaccurate in firgures and some detail, the charges drew needed attention to the captive children.

The trade in children begins in the villages of northeastern Thailand, which as a region has the country's lowest per-capita income. Each spring "brokers" visit many of these communities, tellng heavily indebted farmers of good jobs for their children in Bangkok, Thailand's only large city.

Under normal practice, the broker pays a child's parents a lump sum of $50 to $150 when the child leaves the village. In return, the broker is to get one year's work from the child and can transfer him or her to whomever he wants -- just as the two girls from Tongpun's factory were "sold" after their attempted escape.

Tongpun's story is typical. In March, a man from the Buriram provincial capital showed up in her village, 200 miles northeast of Bangkok.

The year's main rice crop had been planted, and many children were idle since rural children often leave school after the fourth grade. Many farmers were probably wondering how they would meet payments on loans taken at planting time.

Visiting individual houses, the man made an offer many parents could not refuse: payments of $50 in advance every six months for each child sent to Bangkok. He promised they would be well looked after and returned -- or extended, if the parents chose -- at the close of a year.

In the end 40 children, went, Tongpun's father recalled. However, he refused to give his own daughter permission to go. But, Tongpun, having heard of the excitement and glitter of life in Bangkok, stole away one evening and joined the group.

Traveling by train with a woman, Tongpun and four other girls arrived in Bangkok at Hua Lampong rail station. The girls went directly to "volunteer for work," that is, they were displayed to factory foreman who had come to the station. The emloyers usually favor girls over boys, apparently considering them more controllable.

Within hours Tongpun had split up from the other girls and was riding in a taxi toward the Kokhua weaving factory. She does not know quite what happened but she had probably just been "sold," the factory man paying the woman escorting her the $50 plus a commission and making arrangements for furture payments to her parents.

Life at the Kokhua plant quickly cooled Tongpun's enthusiasm for the city. She and 14 other girls worked 12-hour days, seven days a week.

"There were no holidays," Tongpun said.

The girls operated old and poorly maintained looms and spindles. One girl once caught her arm in a spindle, opening a gash that quickly became infected. No doctors were on call, so sick or injured children simply lay down until they were better.

After work the girls went to two rooms elsewhere in the factory to sleep on the floor. There were no mosquito nets, according to Tongpun, but "plenty of mosquitos."

Most days they were not allowed to leave the factory, although sometimes the Chinese woman overseeing the girls gave them 15 cents to buy sweets on the streets.

"When we went out, she went with us," Tongpun said.

The woman apparently counted on intimidation to keep her girls on the tether -- she sometimes beat them when they did not do their work correctly. One day she allowed four girls to go out to buy some things unescorted. Instead, they walked two miles until they found a police officer.

The police promised to bring charges against the factory owner for violating labor laws, which could bring a maximum penalty of six months' inprisonment and a $500 fine.

Tongpun's story is by no means the worst since she has escaped physically and mentally healthy. In 1978, 56 girls were rescued from a candy factory after two of their coworkers died of pneumonia and "heart failure."

There was another case where a textile factory owner kept dogs on the ground floor to keep the children in their rooms upstairs," said a woman at a Bangkok employment agency.

Some girls find themselves taken not to factories but to run-down hotels that function as brothels. Held prisoner inside and brutally initiated in the prostitution trade, they may feel their reputations are ruined and they have no choice but to stay on.

Labor Department Director Vichit Saengthong argues that although this use of children is illegal and morally reprehensible, it cannot fairly be called slavery. He said, "Slavery was abolished in Thailand at the time of King Rama V," whose 42-year-reign began in 1868.

The children work for a specific period of time under a contract, either verbal or written, and the lump sum represents "an advance payment (on wages), not a sale."

Moreover, Vichit and other labor specialists note that the issue is clouded by parental acquiescence. The children are not kidnaped. On the contrary, parents sometimes even bring them to Bangkok and place them in factories.

The key to the problem is rural proverty and disparities of income, which force adults and children to seek work in Bangkok, no matter how bad conditions may be, he said. Citing a raid two months ago on a candy factory, he said, "According to reports I have received, before very long the children came back and worked in the factory again."

Vichit said he had only 60 inspectors to enforce labor laws and they visited only legally registered factories. Requirements that approval from the Labor Department be obtained before hiring children below age 17 in many businesses seem to have had little effect.

In his Geneva testimony, Tim Bond claimed that the police encouraged child labor.

"From labor shops they received an income in return for silence. From brothels they can take their pick for free," he said.

Although the children technically may not qualify as slaves, they are subjected to involuntary seritude. Being kept under lock and key and worked mercilessly for 12 hours a day and more are not the normal expectations of contract workers.