Tian Wenhua, 66-year-old former chairman of the now-bankrupt Sanlu Group, appeared with three other company executives, charged with producing and selling milk laced with melamine, a chemical additive that gave the watered-down product the appearance of higher levels of protein.

At least six children have died and more than 290,000 others been made ill from the contaminated milk.

All four accused face a maximum penalty of death if found guilty.

Outside the courthouse yesterday, a small but vocal group of protesters gathered.

'They should execute them all,' shouted Ms Hua Lian, a 45-year-old woman who described herself as a milk consumer, as roughly half-a-dozen relatives of sick children held up signs seeking justice. 'They have to deal with these people harshly. Otherwise people will never learn.'

Executives at Sanlu have been accused of covering up evidence that Chinese children had developed kidney stones and other complications from drinking the adulterated milk months before the scandal broke in September.

During the hearing, Tian and two of the defendants stood in front of a three-judge panel after being escorted into the courtroom.

The fourth, Wang Yuliang, a former deputy general manager at Sanlu, was in a wheelchair because he lost the use of his legs during a suicide attempt, Xinhua said.

Tian told the court she had learned of consumer complaints about the problematic milk in mid-May, and set up a team to handle the case.

But she also said she did not report the situation to the local authorities in Shijiazhuang, the northern Chinese city where Sanlu is based, until Aug 2.

Sanlu was the first and biggest dairy producer found to have sold milk contaminated with melamine last year.

In all, 22 Chinese dairy firms were found to have sold tainted milk, and the government last week ordered them to pay US$160 million (S$230 million) in compensation to the families of babies that died or fell ill.

However, the families and their lawyers criticised the sum as woefully inadequate, with some parents set to receive only about US$300.

'I'm a farmer. I don't have money to pay for treatment. My son is still sick and he's not been able to get treatment,' shouted one protester outside the court.

Others held up sheets of paper that read: 'The victims have a right to participate in judicial proceedings.'

This reflected an apparently widespread complaint from the victims' relatives that they had not been allowed to tell the courts their version of events, and that the authorities had rejected civil compensation lawsuits.

'We asked to participate in the trial, in the prosecution. We felt that we had a right to participate as we represent the victims,' said lawyer Xu Zhiyong, who is working for a group of people seeking to sue Sanlu and other milk firms. 'But the court refused. We think the court has violated legal procedure by keeping us out.'

Foreign press were not allowed inside the Shijiazhuang court, but Chinese state-run media were let in to publicise the case.

In China, trials are often held behind closed doors and last just one day, with verdicts announced shortly afterwards.

China's efforts to carefully publicise the trials appeared to reflect the government's intent to show both a domestic and international audience it was taking the issue seriously.

In a move underscoring public concerns, China's top product quality watchdog was reported yesterday to be testing tableware made of melamine after reports that the products could be toxic when heated. The utensils were sold in domestic supermarkets and wholesale markets, Xinhua said.

The four Sanlu executives are the highest profile figures to be tried over the scandal, after 17 people, mostly accused of being middlemen, went on trial in recent days.

The milk scandal became a global problem after it emerged that some of the tainted products had been exported, leading to massive recalls of Chinese dairy foods around the world, including in Singapore.

AGENCE FRANCE-PRESSE, ASSOCIATED PRESS, REUTERS