A Chinese court on Thursday sentenced two men to death for their role in a tainted milk scandal that killed at least six children, while the woman most widely blamed for the tragedy got life in jail.

Nearly 300,000 children fell ill last year after drinking milk intentionally laced with melamine, a toxic industrial compound that can give a fake positive on protein tests.

The latest in a string of food safety failures that have blighted the "made in China" brand, it was also one of the worst and prompted an outpouring of public anger.

Beijing may have timed the sentencing to try and tame outrage ahead of China's most important holiday.

The closely watched trial of middlemen and executives from the Sanlu Group, a now bankrupt firm that had failed to report cases of infants getting sick from drinking its products, wrapped up just before the Lunar New Year.

A handful of parents traveled to the gritty industrial town of Shijiazhuang and waited for hours in the freezing cold — at a time when most of the country is planning family reunions — to hear what justice their children would get.

"Spring Festival is coming up, but what happiness is there for us?" said Hou Rongbo, whose son died in early January just a week before his first birthday. Hou believes his death from a leukemia was caused or worsened by melamine that also gave him kidney stones.

Many families have focused their anger on Sanlu's former general manager, Tian Wenhua, and felt betrayed that she would not face execution. Tian pleaded guilty late last year to charges that do not carry the death sentence.

"She should have been shot," said Zheng Shuzhen, a 48-year-old who said her granddaughter died in June of kidney failure after drinking Sanlu milk formula. She said the girl was not on official lists of victims as she died before the scandal came to light.

"So many children died but they kept the official number down so that she could get life (in jail), not death," Zheng added.

Tian was also fined 24.5 million yuan ($3.6 million). Sanlu, partly owned by New Zealand's Fonterra dairy cooperative, was fined 49 million yuan.

Melamine, which can cause kidney stones, is meant to be used in making plastics, fertilisers and even concrete. Its high nitrogen content allows protein levels to appear higher when it is added to milk or animal feed.

POLITICAL VOLATILITY

Claims of official concealment and indifference have turned the milk powder case into a volatile political issue for the ruling Communist Party, which is wary of protests.

Police detained two parents to stop them attending the trial, where they wanted to raise questions about compensation and long-term health problems, fellow activists said on Wednesday.

The family of the first child killed by the tainted milk have now received $29,000, state media said last week.

But many other parents say payouts are too low and limited in their scope, and they fear officials are ignoring or covering up information on the long-term impacts of melamine poisoning.

"What we want is not a verdict. We want the government to properly research the effects of melamine and tell us what to expect. Now melamine is still a blank," said Ma Hongbin, a company technician in the far southern city of Shenzhen. His son Ma Tianxing required an operation to remove kidney stones.

On Thursday, police guarded the courthouse, nudging people away but avoiding confrontation. The session to announce the verdicts and sentences was closed to the public but a court official gave details to reporters.

One of the men sentenced to death was Zhang Yujun, who had made and sold over 600 tonnes of "protein powder" laced with melamine between October 2007 and August 2008, the official China Daily quoted prosecutors as saying earlier this month.

The powder was bought by middlemen who added it to pooled, watered-down milk from farmers that was then sold on to Sanlu. One of these men was also given the death sentence.

A third man was given a suspended death sentence, which usually means life in prison on good behavior. Other defendants received from five years to life imprisonment.

The court had announced it would sentence 21 defendants implicated in the scandal on Thursday afternoon. However, it said shortly before the court opened that nine of them would be sentenced at other courts.