At the end of June, the hospital alerted Fuyang Television, which on July 17 broadcast a programme alerting parents to milk powder and the importance of nutrition. Officials from the Bureau of Commerce and Health and the Quarantine Inspection Bureau then visited the hospital to examine case files and make inquiries.

However, no action was taken over the substandard milk powder until it had been linked to the deaths of 13 babies and the malnourishment of 158.

On April 21 this year, after more complaints from parents and a national broadcast on CCTV, authorities distributed a list of 45 brands of substandard milk powder.

Babies who had been fed the formula had swollen heads and cheeks from fluid retention, but the rest of their bodies were emaciated.

A State Council investigation team found that the number of malnourished babies in Fuyang might have been as high as 354 in the past year, with 15 dead. The Fuyang government insists only 171 babies were affected.

Initial media reports said the problem appeared to be confined to Fuyang and nearby rural areas, but local doctors said they were seeing cases from Huainan , Huaibei and even Henan province .

The Beijing Youth Daily reported substandard powder had also been found in Chongqing , Zhejiang , Guangdong, Hunan , Hubei , Jiangxi , Beijing and Shanghai.

Fuyang's big supermarket chains are reportedly assured of the quality of formula they stock, but small grocery stores in villages are not. Hong Haiyan , the manager of a Hua Lian chain convenience store in Fuyang, said each batch of milk powder delivered to the store was accompanied by results of tests by the Quality Inspection Bureau. 'The problem arises only in rural areas because people are sensitive to prices and only buy low-priced products manufactured by disreputable companies,' she said.

Wang Maoxin , a grocery store owner in Wushipu village, whose stock of 20 packs of formula was seized by officials from the Bureau of Commerce about 10 days ago, said he was supplied by a retailer in Fuyang and had no way of verifying the contents. 'All we know is the list of ingredients on the package,' Mr Wang said.

The general manager of the Guangzhou-based Jinding Dairy Products Company, Su Rurong , said the manufacturing of milk powder was stringently controlled. The Ministry of Light Industry's dairy products division issues a production licence only after it has inspected a factory with the local Quality Inspection Bureau.

Factories must also submit the packaging and a biochemist's report on products to the local department of health before starting production. Products must then be sent to the Quality Inspection Bureau for approval before they can be sold. Throughout the year, there are random tests at factories, while the Bureau of Commerce will also test the products that make it onto the market.

But despite the number of quality tests which baby food products must pass, the Fuyang baby milk scandal shows there is something wrong with the system.

'Who is to tell if these factories are not the main taxpayers in a town and local authorities are protecting them?' asked a Guangzhou doctor.

'It's a case of big investigation, big problem, small investigation, small problem and no investigation, no problem.'

A Guangdong government medical source blamed the lack of action on the number of agencies involved in quality control. 'If a problem is not revealed, nobody knows. If there is a problem, they pass the buck around,' said the source.

While the mainland media has given widespread coverage to the milk powder scandal, there has, curiously, been no expose of factories producing the substandard products. Neither was it questioned why rural residents are bottle-feeding babies when they cannot really afford to.

Ji Liping's family is typical. He is being cared for by his grandfather, Ji Fengxiu , who can barely afford to spend 15 yuan on 400 grams of formula out of an annual income of less than 5,000 yuan. Most of the children's guardians have no choice as their mothers returned to the cities to work after giving birth.

Fuyang and the surrounding areas are one of the mainland's four biggest sources of migrant labour.

Women leave their babies with ageing - and often illiterate - parents thinking that their children can get by on milk powder, but not knowing that these attractive packages contain nothing more than starch, sugar and artificial milk flavouring.

Some doctors are suggesting that parents go back to the basics, given the expense of infant formula.

Cheng Jianhua , a traditional Chinese medicine practitioner, said: 'Milk powder has been on the market for less than 20 years. For generations before, we fed our babies broth skimmed off boiling rice. We then added sauce from cooked vegetables to give the broth more nutrients and the children grew up healthy.'

Lawyer Tong Lihua , who is helping affected parents file lawsuits, says he is in favour of an information system that will allow parents to check the quality of baby food, and he also wants manufacturers of substandard milk powder to be forced to pay compensation.