In a hi-tech fraud run by firms in three EU states, food manufacturers are making bulking agents out of porcine and bovine gristle and bones that help inflate chicken breasts, so that they fetch a higher price.
The Food Standards Agency (FSA) using new scientific techniques detected the swindle as the non-chicken material had been so highly processed that it passed standard DNA tests.
Thousands of restaurateurs and cafe owners are likely to have been conned into buying chicken containing the powder, which binds water into chicken breasts, while diners have been unwittingly consuming traces of other animals when eating out, The Independent reports.
Britain's two million Muslims, Jews and Hindus are forbidden from eating either pork or beef. Muslims would ordinarily eat halal chicken and Jews kosher chicken sold through approved caterers and butchers.
The Hindu Forum of Britain described news of the adulteration, which will be confirmed publicly today, as "shocking and potentially very distressing."
The food regulator acknowledged the serious consequences of its findings. "Use of these proteins does not make chicken products unsafe, but it is important that people are given accurate information about their food," the FSA said.
The fraud has been taking place for at least the past two years, and still continues because of inaction by the authorities in three EU states, believed to be Germany, Netherlands and Spain.
The European Commission rebuffed British demands to ban beef and pork proteins from being added to chicken when first detected in the UK and Ireland in 2001 and 2003.