All four of the Guangdong firms named in the baby milk scandal source their raw materials from outside the province, the provincial quality and technology supervision bureau said yesterday.

Speaking at a press conference, Ren Xiaotie, vice-director of the bureau, said: "All of the milk factories purchase their raw materials from suppliers in Shanxi, Inner Mongolia and Heilongjiang."

The companies, named on Tuesday as selling contaminated products, are the Yashili Group, Scient Infant Nurture Co and Jinding Diary Factory, all from Guangzhou, and the Jinbishi Milk Co from Shenzhen.

Operations at all of the factories have been suspended pending an investigation, Ren said.

Since the baby milk formula scandal broke, Ren said authorities in Guangdong have assessed products from all milk and diary companies in the province.

"All milk and diary products made in Guangdong after Tuesday are qualified and do not contain melamine," he said.

To date, 84 infants in Guangdong have developed kidney stones, the provincial health department said.

Liao Xinbo, its vice-director, told China Daily: "Forty-two babies are in hospital, and one of them is in a critical condition. Twenty-seven are less than a year old."

Over the past week, hospitals across Guangzhou have been filled with anxious parents, wanting checkups for their babies who had consumed the Sanlu formula.

Yesterday alone, Nanfang Hospital received more than 100 babies, it said.

"More than 10 of the babies had kidney stones, but we are not sure if they were caused by the Sanlu baby milk," Ning Xiyuan, a press officer with the hospital, said.

Editor: Yan