China said it would shut small or unregulated food processers, reducing the number of firms by half, but defended the quality of its exports on Wednesday amid a spate of health scares over Chinese-made food and drugs.

The scandals have grabbed global attention after patients in Panama died from poisonous ingredients in medicine and pets died in the United States from substandard feed, while tainted Chinese toothpaste was found in Central America and elsewhere.

China would raise hygiene requirements for food processors and tighten the approval process for new drugs, its quality watchdog said in a notice posted on Wednesday.

"By 2009, the nucognised and accepted by overseas distributors and consumers."

Wang added that China always paid great attention to export quality and had "repeatedly required Chinese exporters to implement contracts strictly and to deliver quality to importers and meet regulations in importing countries".

China's exports would not be impacted by several recent cases, he said, answering a question about whether food safety issues could jeopardise trade.

Scandals involving substandard food or medicines are reported by Chinese media almost every day.

Public fears about food safety grew in 2004, when at least 13 babies died of malnutrition in Anhui province, in eastern China, after they were fed fake milk powder with no nutritional value.

In the latest case, state media reported that a market in the southern boomtown of Shenzhen was under investigation for possibly selling meat from sick and dying pigs.

China executed a former drug and food safety chief on Tuesday for corruption in an unusually swift sentence amid the health scandals that have stained the "made in China" brand.