The slave scandal that has rocked China during the past week would not have been exposed, and in all likelihood would have continued untroubled, were it not for journalist Fu Zhenzhong and the Henan TV station for which he works.

About 1000 children as young as seven - along with many adults, some of whom were mentally impaired - had been held captive for months and years to work as slaves making bricks for 16 hours a day at kilns in China's dirt-poor northern Shanxi and Henan provinces.

The police did nothing. The state-controlled All China Federation of Trade Unions did nothing. The local Government did nothing.

Communist Party officials did nothing. Indeed, the party chief in Hongtong county, Shanxi province, was the father of the owner of a kiln with 31 slaves, where a worker was beaten to death.

As rumours spread, more than 400 parents of children who had disappeared posted a desperate letter online urging investigation of the kilns, where they believed their children were being held. No one in authority followed it up.

In a final throw of the dice, a group of parents contacted Fu, a prominent TV reporter in his early 30s and a regular face on the nightly news. He met them at the TV station, heard them out and was convinced.

He then travelled to neighbouring Shanxi province three times, accompanied by some of the parents, and called on more than 100 brick companies, concealing his identity, secretly filming what he saw, including compounds guarded by thugs with dogs.

He told China Youth Daily: "I've been working as a journalist for more than 10 years. I have witnessed disastrous fires and terrible road accidents, but I've never seen anything as heart-breaking as this. The children were so young.

"And the biggest obstacle we met in uncovering the truth was that the local governments refused to co-operate. Not only were they utterly lacking in sympathy, some even tried to stop us saving the children."

In Yongji city, Fu said, a boy called Zhu Guanghui was rescued from one kiln and placed in the temporary care of the local Government's labour supervision office. But the office supervisor, named Feng, then sold Zhu to another works for a $50 fee, which he pocketed.

In the same city, Fu said, when he discovered 17-year-old Wu Shudong being held as a slave, the kiln owner replied: "I bought him for $65. I'll beat anybody who tries to get him out."

When Fu and the group of parents accompanying him reported the case to the police, the police backed the kiln owner, saying he had paid for the youth.

After compiling sufficient raw footage from Fu's forays into the brick fields, Henan TV - owned by the provincial Government - broadcast his report at 7.30pm on May 19. Early the next morning, the station's main gate was surrounded by several hundred parents calling for help. Some had seen their children for the first time in years in the TV report.

Most of the other media in Henan followed up Fu's report and within a fortnight the story had been picked up by the national broadcaster, CCTV.

The CCTV report, making substantial use of film shot by Fu, caused a national shockwave.

Fu was interviewed at length by, the leading Henan internet news service. But the interview has since been removed from the Dahe website.

Fu has declined to answer calls from The Australian and other media. It appears the story eventually became too hot to handle.

President Hu Jintao ordered a full investigation.

But the focus has swiftly shifted from tracking the collusive web of government and party officials, police and kiln owners, to naming a few scapegoat brick work bosses.

The internet bureau of the Communist Party of China's central office of external communication, a core propaganda arm, issued a firm instruction last weekend that "regarding the 'Shanxi illegal brick kilns' event, all websites should reinforce positive propaganda, place more emphasis on the forceful measures that the central and local governments have already taken, and stop posting commentaries on these news reports. Harmful information that uses this event to attack the party and the Government should be deleted as soon as possible. All local communication offices should enhance their instruction, supervision and inspection."

Wang Dongji, the local party chief whose son owned a kiln where a slave worker was beaten to death, was expelled from the Communist Party on Monday.

Heng Tonghan, the manager of that kiln, was arrested on Saturday in nearby Hubei province after a $3500 reward had been offered for his capture.

Despite the party's efforts to dampen commentaries on the case, they have continued in English language papers in China.

In the Shanghai Daily on Tuesday, Wu Jiayin blamed "the evil minds of some corrupt officials. They either turned a blind eye to what was happening or were accomplices with the evil kiln owners."

Another Shanghai paper, the Oriental Morning Post, said many local officials kept kiln owners informed of any interest from higher authorities so they could destroy evidence.

And the China Daily website published a commentary by You Nuo on Monday, headlined "We need investigative journalists", which said: "Similar shocking activities may continue here and there if the loopholes in the system are not closed. One loophole is the lack of investigative reporting. The other is corruption among law enforcement.