China executed two people Tuesday for their roles in a tainted milk powder scandal in which at least six children died and more than 300,000 became sick.

Zhang Yujun was executed for endangering public safety and Geng Jinping was executed for producing and selling toxic food, according to the official Xinhua News Agency.

Their sentences were upheld in March by an appellate court in the northern city of Shijiazhuang. China requires death sentences to receive final approval from the Supreme People's Court in Beijing, after which most are carried out by lethal injection.

Xinhua said news of the execution had been issued by the Shijiazhuang Municipal Intermediate People's Court, although a court clerk who answered the phone Tuesday said he was unable to confirm the sentences had been carried out.

The case was one of China's worst-ever food safety scandals, involving tainting of infant formula with the industrial chemical melamine, which can cause kidney stones and kidney failure.

Melamine, used in the manufacture of plastics and fertilizer, was added to watered-down milk to fool inspectors testing for protein, and to boost profits.

Zhang, a cattle farmer, and Geng both had been convicted of producing and selling a phony protein powder containing melamine, much of it to producers who sold tainted milk to the now-defunct Sanlu Group Co., at the time one of China's biggest dairies. Geng's brother, Geng Jinzhu, was given eight years and his sentence was upheld Thursday.

In all 21 people were tried and sentenced in January over the scandal, including Sanlu's general manager, Tian Wenhua, who was given a life sentence after pleading guilty to charges of producing and selling fake or substandard products.

Three other former Sanlu executives were given between five years and 15 years in prison. A total of 21 defendants were being sentenced Thursday in connection with the case.

The harsh sentences underscored the government's resolve in tackling recurring food safety problems and an eagerness by the Communist leadership to move past the embarrassing scandal.

However, no public investigation was ever made into accusations that news of the melamine tainting was suppressed ahead of last year's Beijing Olympic Games because the government did not want it overshadowing the prestigious event.