China has executed two people for their role in a scandal involving tainted milk powder that resulted in six children dying, officials have said.

More than 300,000 other infants were made ill from milk powder contaminated with melamine, an industrial chemical used to make plastics and fertiliser.

Zhang Yujun and Geng Jinping are the only people to have been executed over the scandal, court officials said.

Nineteen other people were sentenced to prison terms.

Zhang Yujun was convicted of endangering public safety by dangerous means, for selling more than 770 tonnes of the tainted milk powder from July 2007 to August 2008, the official Xinhua news agency said.

Geng Jinping, who managed a milk production centre, was convicted of supplying milk containing melamine to the now-bankrupt Sanlu Group and other dairies.

The two men were sentenced in January in Shijiazhuang, capital of Hebei, where Sanlu was based. Their appeals were rejected by the Hebei Provincial Higher People’s Court in March.

Xinhua said the executions were carried out on Tuesday, but did not say where.

Public outrage

Melamine is used in the making of plastics and fertilisers. When added to food products it indicates a higher apparent protein content but can cause kidney stones and kidney failure.

Milk dealers and middlemen, including Zhang and Geng, sold the milk to major dairy companies who failed to test it for its purity and nutritional value.

Sanlu had been China’s largest seller of milk powder until news of the racket broke in mid-September last year, Xinhua said.

It emerged that Sanlu had known it was selling toxic milk – and allowed around 900 tonnes of it to leave its dairies before it stopped production.

The company’s former chairwoman, Tian Wenhua, was sentenced to life in prison in January this year after pleading guilty to producing and selling fake or substandard milk.

She was the highest-ranking executive charged over the scandal.

The case provoked widespread public outrage in China and came after a series of similar food safety incidents, including another one of contaminated milk powder four years previously which left 13 babies dead.

It led to product recalls across the globe, and further damaged China’s reputation for producing safe and reliable products, correspondents say.

In December 2008, the government ordered 22 firms implicated in the tainted milk to pay a total of 1.1bn yuan ($161m; £97.5m) to the hundreds of thousands of families involved.

China’s supreme court has not responded to an appeal from more than 200 families that the compensation was inadequate.

Lawyers acting for some of the families have said the government told local authorities to negotiate with the families to reach a settlement.

“We have handled over 400 cases… [and] more than 100 families have not yet reached an agreement with their local government on a satisfying compensation,” one of the lawyers, Xu Zhiyong, told the BBC.

Another lawyer said the problem with the tainted milk stemmed from an inadequate regulatory system.

“It’s hard to understand why these people are give such harsh punishment because generally speaking… there is a lack of monitoring and regulation,” said Li Fangping.

“It’s the food supervision and inspection authorities that are responsible for this.”