China has ordered a probe after a report that unsafe vaccines led to the deaths of four children and rendered 74 others ill in the country's latest product-quality scare.
The order by the Ministry of Health came after the China Economic Times on Wednesday reported unsafe vaccines for encephalitis, hepatitis B, rabies and other illnesses were being used in the northern province of Shanxi.
The report said the problem vaccines had been sold in the province since 2006.
Neither the media report nor the ministry's order made it clear whether the vaccines themselves were dangerous or whether they had failed to protect children from illness.
Xinhua news agency quoted a top official with the Shanxi Health Department as denying the allegations made in the report.
In a statement posted on its website Wednesday announcing the investigation order, the health ministry said it had investigated earlier reports of bad vaccines in 2008, finding no problems.
China's huge food and drug industries are notoriously scandal-prone, with regular reports of dangerous products on the market, leading to health problems and even deaths among consumers.
In 2008, China's dairy sector was rocked by the widespread contamination of milk supplies with the industrial chemical melamine, which was added to give the appearance of higher protein content.
Six babies died and 300,000 others fell ill after being fed tainted baby formula, according to government figures.