Government ministers were warned in 2011 that horsemeat was illegally entering the human food chain, it was claimed.
John Young, a former manager at the Meat Hygiene Service, now part of the Food Standards Agency (FSA), told the Sunday Times he helped draft a letter to the Department for Environment, Food and Rural Affairs (Defra) in April that year.
But he told the paper the letter to former minister Sir Jim Paice on behalf of Britain's largest horse meat exporter, High Peak Meat Exports, which warned that flesh with possible drug residue getting into food could blow up into a scandal, was ignored.
In the letter the company warned the Government that its passport scheme designed to stop meat containing the anti-inflammatory drug phenylbutazone, known as bute, getting into the food chain was not working, calling it a "debacle".
Wholesaler Castell Howell have contacted customers after a 'possible contamination' of cottage pies.
The Food Standards Agency (FSA) has just announced it will extend its UK-wide survey of burgers and similar beef products.
The horsemeat scandal continues to diminish public confidence in the food industry, an ITV News Index poll finds.