BEIJING—China is probing the death of a baby and the development of kidney stones in dozens of others who may have drunk the same milk formula, a grim reminder of a milk-powder scandal that killed 13 infants four years ago.

State-run Xinhua news agency quoted doctors at a hospital in northwestern Gansu province as saying on Wednesday that "fake milk powder" from one brand could have been responsible for kidney stones developing in 14 infants aged under 11 months.

A rash of other cases of babies developing kidney stones had since emerged in six other provinces and regions, Xinhua said on Thursday, citing local media reports.

Parents of the affected babies, mostly from poor and remote areas, said they bought the milk powder at much cheaper prices than usual.

Health and quality officials were investigating whether the babies had drunk milk formula marked "Sanlu", and had sent samples to a state-run laboratory.

Gansu health authorities were aware of the problem as early as July 16, after a local hospital reported seeing 16 babies with kidney stones who had all drunk the same brand of formula, without explaining the delay in disclosure.

Dozens of other cases of babies developing kidney stones had been reported in Gansu this year, after none was reported in 2006 and 2007. It was not clear whether they had drunk the same brand of milk formula.

Cases of babies developing kidney stones had since emerged in two other hospitals in Gansu and also in Jiangsu, Shandong, Hunan, Anhui, Ningxia and Shaanxi, Xinhua said.

A company spokesman for dairy company Sanlu Group said the milk powder may have been mislabelled and that "someone" might be counterfeiting their product, Xinhua said.

The company was awaiting results of tests and had "more than 1,000 employees" conducting their own investigations across China, Xinhua quoted a Sanlu spokesman surnamed Cui as saying.

In 2005, authorities in the northern port city of Tianjin seized hundreds of cases of mislabelled Sanlu-brand yoghurt.

Sanlu is is partly owned by New Zealand dairy export giant Fonterra Co-operative Group Ltd. China is the world's second-biggest baby milk powder market.

Kidney stones are small, solid masses that form when salts or minerals normally found in urine crystallise inside the kidney.

If they become large enough, they can move out of the kidney, cause infection and lead to permanent kidney damage.

In 2004, at least 13 babies in eastern Anhui province died after drinking fake milk powder that investigators later found had no nutritional value, a scandal that rocked the country and triggered widespread investigations into food and health safety.