Braving the windchill by a highway in Baise City of south China's Guangxi, 18-year-old Vietnamese Lau Mi Lenh and his family desperately tried to hitch a lift to their dreamland of neighboring Guangdong Province.

Hailing from a village in the Vietnamese province of Nghe An, Lau and his eight relatives had sneaked into China by themselves, hoping to find a job in Guangdong, as he had heard that the bustling coastal province could guarantee a handsome income for people like them.

It wasn't to be, and the illegal immigrant told Xinhua his tale from a Chinese jail cell.

He is among booming numbers of people without valid entry and employment paperwork, particularly from southeast Asia, that are flooding into the country's eastern seaboard, a part of China that is increasingly looking to the black market to fill gaps in affordable labor.

The issue is once again in the spotlight after two groups of Vietnamese stowaways, a total of eight people, were detained by local police in Baise on Friday.

Regional border control police of Guangxi Zhuang Autonomous Region intercepted 4,500 illegal foreign laborers in 2012, and though the number dipped to a little over 3,500 in 2013, police say there are "definitely ones that are at large."

The illegal laborers, taking advantage of the many trails that snake through the China-Vietnam border area, stick their necks out to bypass the checkpoints in Guangxi to reach the eastern paradise of their dreams.

Mi Lenh said that his family moved heaven and earth to get to Baise, eventually enduring an anxious 24-hour ride in a minivan to get there.

"I was prepared to labor in jobs planting eucalyptus or sugarcane even in the countryside of Guangdong," he explained.

ILLEGAL CHAIN

China's black market of foreign labor is booming on the back of a shift in the country's own labor forces from east to west, driving human traffickers, or "traders" as they are dubbed, to transport cheap labor from abroad into the eastern areas like Guangdong, Fujian and Zhejiang.

Ah Xiang, a trader detained by police in Guangxi, said that they usually lure poverty-stricken foreigners willing to work in China with blandishments about the working opportunities, then charge "registration fees" before transporting them into Chinese factories.

"We would negotiate with the factory owners in advance to remove any possible stumbling blocks, and then the procedures would go smoothly," she said.

According to Ah Xiang, foreign laborers are becoming increasingly popular in factories in the east, as domestic workers are thin on the ground, while foreigners tend to be cheaper, more "well-behaved" and "quiet."

But the opportunities to make more money in China are often outweighed by terrible working and living conditions, Ah Xiang added, pointing out that it is hard to guarantee the rights of the illegal workers.

Experts attribute the phenomenon to a wide range of factors, including rising labor costs in China as well as loose supervision.

One of the underlying reasons for the rampant black market in foreign labor is that China's coastal cities have come under pressure from a severe shortfall in labor resources, according to Yu Yimao, captain of Baise's border control police.

In February, a survey by the Guangzhou Human Resource Market Service Center showed a shortfall of 123,300 workers in Guangzhou, capital city of Guangdong. A similar warning was issued later by the Fujian provincial government, cautioning that the province needs 80,000 laborers to fill the gap.

Meanwhile, the cost of domestic labor is on the rise.

Construction worker Li Deqin said that the daily salary for people like him used to be about 80 yuan (13 U.S. dollars), but now they command at least 180 yuan.

That is a huge contrast to many foreign workers like Mi Lenh, who barely makes 50 yuan each day in Vietnam.

"I heard that even stowaways can make more than 100 yuan a day in China," the young Vietnamese said.

While his dreams have now become castles in the air, many others are still falling for the bait, and authorities have called for a taming of the black market with a spate of proposed legal measures.

Xu Ningning, deputy secretary-general of the China-ASEAN Business Council, said that China needs to ramp up supervision to tackle the problem, for that is in the interest of both foreign workers and domestic factories.

"I think that the government could work with the Association of Southeast Asian Nations to figure out a mechanism to ease the labor pressure and guarantee the rights of workers," Xu said.

He suggested that the problem could be solved by qualifying and legalizing more foreign laborers to work in China under government supervision.