Experts investigating China's latest product safety scandal found no link between a brand of milk powder and apparent breast growth in three babies, the Health Ministry announced Sunday.

The ministry launched an investigation following parents' complaints that the babies developed breasts after drinking formula made by Synutra International Inc. The China-based company has rejected the complaint.

Researchers "found nothing abnormal about the amount of hormones contained in milk powder from Synutra and other brands" after testing samples from 14 producers, said a ministry spokesman, Deng Haihua.

In the Synutra samples, "no banned additional sex hormones were found" and naturally occurring hormones in the milk were within normal ranges, Deng told a news conference.

The ministry tested 42 samples of Synutra milk, including some from the families' homes in the central province of Hubei, and 31 samples from other Chinese and foreign suppliers.

A ministry "experts group" concluded breast growth in the three Hubei cases "has no connection to the Synutra milk powder," he said.

State media have said the babies with apparent breast growth were found to have abnormal levels of the hormones estradiol and prolactin, which stimulate lactation, or the making of breast milk.

The babies went through "mini-puberty" but their bones and body size are normal for their age, said a physician at the news conference, Wu Xueyan, the director of endocrynology for Peking Union Hospital.

The breast growth is "within normal physical range" and less than what would be caused by large amounts of external estrogen, the female sex hormone, Wu said.

China has been shaken by a series of safety incidents, some of them fatal, involving products including toxic toothpaste, faulty tires and tainted milk.

In 2008, more than 300,000 children were sickened and six died after drinking infant formula tainted by the industrial chemical melamine that suppliers added to fool tests for protein content.

That scandal led to prison terms for dairy executives deemed responsible and a shake-up of the Chinese milk industry.