The Ministry of Health has ordered local health authorities to inspect markets and restaurants, vowing to prosecute those who are still selling or serving red-yolk duck eggs.

The move follows revelations that farmers had been feeding cancer-causing dyes to ducks in order to produce the valued red-yolk eggs.

In an urgent circular to all provinces, regions and China Center for Disease Control and Prevention, the ministry said the Sudan range of industrial dyes was banned as a food additive under the national regulation on the use of food additives.

It required local health inspection departments to launch immediate checks on the sales of eggs from Beijing and Hebei Province, where eggs containing the carcinogenic dye have been found.

Anyone who continued serving or selling the eggs must be prosecuted, said the ministry, adding the inspections must be reported to the local governments and the ministry.

Red Sudan dyes are used in the leather and fabric industries. The International Agency for Research on Cancer, part of the World Health Organization, assessed Sudan dyes as Group 3 genotoxic carcinogens.

Last year, the ministry reiterated the ban on production, sales and use of Sudan dyes in food, after it was found in some brands of pepper sauce, chili oil and fast food giant KFC's New Orleans roast chicken wings.

It was also found by the United Kingdom Food Standards Agency in February 2005 in a batch of chili powder sold by Premier Foods, one of the country's largest food and beverage companies.

Chinese red-yolk salted duck eggs are commonly thought to be more nutritious than yellow-yolk eggs and so are usually more expensive.

An investigation showed farmers in Hebei bought a "red drug" from a trader and used it in duck feed to make the ducks produce red-yolk eggs.

The contamination was first disclosed in a weekly quality report program on China Central Television. The Beijing authorities immediately banned the sales of red-yolk eggs from Hebei and advised consumers to return them.

The General Administration of Quality Supervision has launched nationwide inspections of egg products and poultry meat.

Beijing officials have seized at least 1,159 kilograms of red-yolk eggs, and the eggs have been banned in markets in Chengduin Sichuan Province and Guangzhou in Guangdong Province.

(Xinhua News Agency November 17, 2006)