Health officials in China say ducks that produce some red-yolk salted eggs are being fed a cancer-causing chemical to create the color.
In Beijing, authorities have banned the sale of the eggs pending the outcome of an investigation, Xinhua, the official government news agency said.
Ironically, red-yolk eggs often cost more because they are believed to be healthier.
Authorities say that some farmers in Hebei Province have been adding a "red drug" to duck feed to make the yolks redder. The drug is believed to contain Sudan IV, an industrial dye and suspected carcinogen that is banned from food in China and many other countries.
The use of the dye was exposed by a report on China Central Television.
Copyright 2006 by United Press International