And Li Dehui, 22, another worker, said he was taken to the secret brick kiln after he had read a recruitment poster and been fooled into entering a van owned by an illegal job recruiter.

Li, who is from Chongqing, said he was forced to sign an IOU after he had arrived at the kiln. The paper signified that he was indebted for the 400 yuan (US$61.5) the manager of the brick kiln had paid to buy him from the job recruiter.

"The boss said I had to pay the debt if I wanted to leave the brick kiln," Li said. "But I had no money, not even a penny."

Li said he turned to his family for help.

"After the boss began to trust me, I was able to call my father and tell him what had happened on me," he said.

Li's father, Li Xiuquan, came to Huizhou and sought help from local government departments.

Li said he lived in a wooden house with poor conditions and ate bad food.

The workers, who often had to stay on the job until midnight, would receive only 5 yuan for three months of toil, Li said.

In addition to being fooled into taking the job by illegal recruiters, the workers at the brick kiln had been directly kidnapped from the streets, Li said.

Huizhou officials said the brick kiln had been operating for many years.

They said it was difficult to shut down because it lay in the city's remote mountainous area.

Authorities said there might be more than a dozen such kilns in Huizhou, a city bordering the Shenzhen special economic zone,.

Authorities have promised to start a special campaign to crack down on illegal brick kilns throughout the city.