The vast majority of China's livestock feed producers have complied with a ban on using the chemical melamine, but banned additives are still getting through, Agriculture Minister Sun Zhengcai said Monday.

He said tests carried out on more than 22,700 feed batches since a scandal over the use of the industrial chemical in milk supplies had found that 97.6 percent of feed producers were clean, the Beijing News said.

However, speaking on a tour of egg producers in Hebei province in northern China, he acknowledged that some businesses still used banned additives that posed a potential health risk.

"There are still some livestock feed enterprises that illegally add banned medications and harmful chemicals," Sun was quoted as saying.

"Some livestock feed enterprises do not strictly control what enters the factory, feed formulas are improper, and adulteration with fake ingredients still exists."

Sun's comments came as China tries to limit the global damage to its image caused by the discovery that melamine, normally used in making plastics, was added to milk products.

At least four babies died of kidney failure and 53,000 children fell sick after drinking products contaminated by the chemical, which had been added to watered-down milk to make it appear richer in protein.

It led to massive recalls of Chinese food products containing milk at home and abroad.

Last week, eggs were pulled off supermarket shelves in China after those produced by a major egg company were found also to contain melamine, raising fears of wider contamination.