A English county has confirmed that horse meat has been found in cottage pies served at 47 of the county's schools.
Lancashire County Council said it has withdrawn the products from all of the schools' kitchens, but it will not say which schools served the contaminated meat.
The news comes as the Food Standards Agency (FSA) published the results of tests on all supermarket beef products, revealing that 29 of the 2,501 samples contained horse meat.
There are around 900 more test results to be released, with the next batch to be revealed next Friday.
The agency's chief scientist, Andrew Wadge, told Sky News that he was reassured by the results so far, but retailers need to take responsibility.
"If you're in the business of selling food, you have to make sure you're clear to consumers that what you sell is what it says on label," he said.
It has also been revealed that Whitbread, one of the U.K.'s largest hospitality companies, said horse meat was found in its beef lasagna and burgers.
The meals were sold at Whitbread companies Premier Inn, Brewers Fayre, Beefeater Grill and Table Table.
The firm said the products had been removed from their menus and will not be replaced until further testing has been carried out.
Officials also said burgers containing horse meat had been supplied to hospitals in Northern Ireland.
David Bingham from the health service's Business Services Organization, which provides meat for the health trusts, said a range from a company in the Republic of Ireland had been withdrawn.
After the results on the school meals were revealed, Lancashire County Councilor Susie Charles said: "Relatively few schools in Lancashire use this particular product, but our priority is to provide absolute assurance that meals contain what the label says - having discovered this one doesn't, we have no hesitation in removing it from menus.
"This does not appear to be a food safety issue but I've no doubt parents will agree we need to take a very firm line with suppliers, and it is a credit to our officers that we have been able to quickly identify the problem and take the product off the menus."
A Department of Education spokesperson also gave reassurances that it was not a food safety concern.
"While the Food Standards Agency is clear there is no identified public health risk, this nevertheless represents a serious and unacceptable breach of trust," the spokesperson said.
"Suppliers and caterers should be urgently reassuring schools and parents about the action they are taking."