BEIJING, June 17 (Xinhua) -- Chinese police have detained 168 people in a large-scale rescue operation of slave laborers in small brick kilns and mines in Shanxi and Henan provinces in central China.

    Forty-eight people who were allegedly to have been involved in the illegal use of slave labor were detained in Shanxi, while the others were detained in Henan, according to local police sources.

    By Saturday, 351 people, including 22 under the age of 18, were freed after police raided more than 3,700 small brick kilns and coal mines, many of them are unlicensed, in Shanxi, the country's biggest coal producer.

    Heng Tinghan, a 42-year-old foreman of a brick kiln in Hongtong county in Shanxi was arrested Saturday after the Ministry of Public Security issued a warrant for his capture.

    Heng is suspected of forcing people to work as slaves in his brick kiln since March 2006. It's alleged that one worker died and20 other were injured after being forced to endure extremely cruel working conditions at the mine.

    In central China's agricultural province of Henan, a major source of slave laborers, police have detained 120 suspects.

    Police in Henan say they have freed 217 slave laborers, including 29 aged under 18 and 10 who are mentally-handicapped, according to Henan provincial public security bureau.

    Five gangs involved in organizing slave workers for the brick kilns, in Zhengzhou, capital of Henan, have been busted and 13 members were arrested.

    The use of slave workers was first reported by a Henan television station after an open "call-for-help" was posted on the Internet earlier this month by more than 400 fathers in Henan who believe their missing children had been sold to the small brick kilns as slave workers.

    The fathers said most of their children were abducted or tricked at railway and bus stations and the streets in Zhengzhou and sold to Shanxi by traffickers for 500 yuan (65 U.S. dollars).

    Some parents of the missing children in Henan had gone to brick kilns in Shanxi to try rescue their children before the salve labor scandal was widely reported by domestic media.

    Many of the slaves were forced to work 14 to 20 hours a day without payment. They would face beatings if they were caught trying to escape.

    The scandal has also aroused concerns from China's top authorities.

    A working team comprised of officials from the Ministry of Public Security, the Ministry of Labor and Social Security and the All-China Federation of Trade Unions has arrived in Shanxi to investigate the slave labor case.

    Sun Baosu, vice minister of labor and social security, said the case "had an extremely bad impact", while inspecting a burned shed where slave workers had lived at a brick kiln of Caosheng village in Hongtong county.

    Sun, who is also head of the team, pledged that those involved in the sale and use of salve workers would be punished severely.

    In Yuncheng city in northern Shanxi, public security, labor and trade union authorities returned 210 freed salve workers to their homes.