BEIJING — China's premier promised Saturday to improve food safety, as a welfare group said almost a dozen Chinese orphans were among the 50,000 children sickened after drinking milk contaminated with an industrial chemical.

The 11 children, who live in orphanages around the country, are being treated for kidney stones at hospitals after drinking Sanlu brand powdered milk, the Half the Sky Foundation said on its Web site.

"All orphanages using identified tainted brands have changed to either fresh milk or to a brand that has been identified as safe," said Jenny Bowen, executive director of the Berkeley, Calif.-based group that provides services, supplies and work crews to 41 Chinese orphanages.

The cases were part of a growing scandal surrounding milk containing melamine, a chemical used to make plastics and fertilizer. In China, some 54,000 children have developed kidney stones or other illnesses after drinking contaminated baby formula. Four deaths have been blamed on the bad milk.

In a speech at the World Economic Forum in the eastern port city of Tianjin, Chinese Premier Wen Jiabao reassured participants China was serious about bettering its food safety record.

"We plan not only to revitalize the food industry and the milk powder industry, we will try to ensure that all China-made products are safe for consumers and consumers can buy with assurance," Wen said.

He did not announce any new initiatives but promised the government will make efforts to instill business ethics after a string of product safety disasters.

Chinese suppliers trying to cut costs are believed to have diluted their milk while adding melamine because its high nitrogen content can fool tests aimed at verifying protein levels.

Since the scandal erupted earlier this month, melamine-tainted products have turned up in an increasing number of Chinese-made exports abroad — from candies to yogurt to rice balls.

Wen defended the handling of the crisis by Beijing, which has in the past been accused of being reluctant to come clean in situations that could potentially embarrass the communist leadership.

"When this kind of problem of food safety occurs, we do not cover it up," Wen said. "We face it candidly and have taken bold moves to address it. I think this has laid a good foundation for resolving problems."

Health experts say ingesting a small amount of melamine poses no danger, but in larger doses, the chemical can cause kidney stones and lead to kidney failure. Infants are particularly vulnerable.

According to Bowen, two of the orphans each were sickened in welfare institutes in Tianjin, Henan province in central China, and Guangdong province in the south. Another five with kidney stones lived in Hunan province, also in the south, she said.

Another eight welfare institutions were using brands that have tested positive for toxins but none of the children became sick, she said.

Bowen said the foundation had contacted China's Ministry of Civil Affairs, which is working to provide guidance to institutes that house babies.

A woman who answered the telephone Saturday at the ministry said a letter had been sent out a few days ago to local governments urging them to inspect orphanages.