Illegal milk from the offspring of a cloned cow is being sold in British stores, The Sun reported.
The Food Standards agency are urgently investigating after reports that a British farmer admitted using milk from the cow bred from a clone.
The dairy farmer — who wanted to stay anonymous — said he used the milk as part of his daily production.
Under European law, food and drink produced from cloned animals must pass a safety evaluation and get approval before going on shop shelves.
The FSA, the UK body responsible for assessing food produced by cloned animals and their offspring, said it has never authorized the food for mass sale - or been asked to do so.
"Since 2007 the FSA interpretation of the law has been that meat and products from clones and their offspring are considered novel foods and would therefore need to be authorized before being placed on the market," a spokeswoman said.
"As the UK authority responsible for accepting novel food applications, the agency has not received any applications relating to cloning and no authorizations have been made," she said. "The agency will, of course, investigate any reports of unauthorized novel foods entering the food chain."
A spokeswoman for the Department for Environment, Food and Rural Affairs (Defra) referred inquiries to the FSA.
There was concern about calves born to cloned parents three years ago when it emerged that a calf from a cloned cow was born on a British farm.
Dundee Paradise was said to have been born to a surrogate mother on a Midlands farm after she was flown into Britain as a frozen embryo.
Her mother was created in the United States using cells from the ear of a champion dairy Holstein, according to reports.
Later that year, public outrage caused Dundee Paradise and her brother, Dundee Paratrooper, to be withdrawn from an auction but it is thought they went on sale privately instead.