More than 1,000 people, many of them young children, have been forced to work as slaves in a brutal human trafficking ring in China that has shocked and outraged the nation, police say.
More than 500 people have already been rescued in recent days from brick yards and coal mines that were run with exceptional ruthlessness in two provinces in central and northern China.
Media reports described freed workers, some as young as eight, as having been beaten, nearly starved and forced to work long hours under appalling conditions, apparently with the involvement of some local police and officials.
At least one man was beaten to death, according to a confession by a brickyard boss on television, with other reports saying the slave trade had been going on since at least March - and perhaps for years.
"So far, we have rescued more than 200 people including over 40 children," an official with the Henan provincial public security department, who gave only his surname of Dang, told AFP by phone.
"They were abducted and sold to brick kilns in Shanxi and Henan provinces."
Li Fulin, vice-director of public security in Shanxi, said in a statement that separate police raids there had freed another 251 people. Xinhua news agency later said another 80 had been rescued in Shanxi.
Officials in both provinces said investigations were continuing in a bid to free hundreds more believed to be enslaved.
"It is hard to estimate the number of missing people before the investigation finishes, but there are probably more than 1,000," Dang said.
The scandal has caused alarm among the highest ranks of China's ruling Communist Party, with President Hu Jintao and Premier Wen Jiabao issuing orders to deal with the situation, the China News Service reported.
However no comments from the two leaders were immediately released.
State television aired disturbing images of abused and emaciated workers living in squalid conditions at a brick factory in the city of Hongtong in Shanxi province.
Workers said many of them tried to escape but most were caught and brought back. Vicious dogs were used to stop workers breaking out.
The revelations have sparked nationwide disgust, and editorials in state newspapers on Friday called for investigations into allegations that local bosses were guilty of collusion.
"How could officials in the area have connived with such audacious and appalling behaviour to allow this situation to arise under their very eyes?" asked the People's Daily, the main mouthpiece for the Communist Party.
One of the brickyards was run by the son of a local Communist Party boss, the nation's main union body said in comments carried in the state press.
The scandal adds to other embarrassing revelations this week about the plight of Chinese workers, including reports that children were being used to make merchandise for the 2008 Beijing Olympics.
In another scandal, more than 500 children were found working ultra-long hours for up to six days a week in a light industry factory under a so-called "work-study" program authorised by their school.
