Horsemeat has been found in school dinners, pub meals and food prepared for hospitals in the UK, it has been revealed.
As the scandal widens, the Food Standards Agency (FSA) also said it had raided three more meat plants this week.
Lancashire County Council confirmed that horsemeat was detected in cottage pies it served at 47 schools.
The council said it has withdrawn the affected products from all of the schools' kitchens but refuses to say which ones served the contaminated meat.
Lancashire County Councillor 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."
Contaminated beef lasagne and burgers 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.
Compass, which operates across the UK and Ireland (OTC BB: IRLD - news) , said that sites where it operates had been supplied with burgers from Rangeland - an Irish processor found to have had two consignments of meat with horse DNA.
They company said: "This is totally unacceptable. We have informed all of the affected sites of these developments, explained the actions we have taken and issued unreserved apologies."
Compass said 13 sites in the Republic and 27 in Northern Ireland, including two secondary schools, were supplied with burgers from Rangeland, the 4oz Rangeburgers which have been found to contain 5-30% horse DNA.
The company has catering operations at 7,000 sites and that most of the sites using Rangeland product were offices.
None of the sites where food was withdrawn were hospitals or sporting venues, Compass confirmed.
Compass said it had withdrawn Rangeland produce on February 5, which included 180 cases of suspect burgers.
Officials have also said that burgers containing horsemeat had been supplied to hospitals in Northern Ireland.
Whitbread said they had sent 30 products to be tested and the company received the results on Thursday afternoon.
A spokesman said: "We are shocked and disappointed at this failure of the processed meat supply chain.
"As a responsible business we shall work with the FSA to implement a robust testing regime to avoid this happening in the future. We would like to sincerely apologise to our customers for any concerns or inconvenience that this may cause."
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 horsemeat.
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.
The FSA said it had raided two plants in Tottenham, north London, and one in Hull, Yorkshire, on Thursday.
The agency said it had collected meat samples for testing, as well as computers and documentary evidence.
One of the plants raided in north London, Dinos & Sons Continental Foods, said it was "co-operating with local trading standards officers and the FSA".
"Dinos & Sons has been asked to clarify its position in respect of the transportation and storage of frozen beef that was imported by, and belonged to, a third party that the FSA is investigating.
"Dinos & Sons did not keep this frozen beef in the same premises as its own products and there was therefore no possibility of any cross-contamination.
"At no time has Dinos & Sons produced or manufactured anything that is under investigation or is the subject of any possible contamination or mislabelling.
"There is no suggestion whatsoever that Dinos & Sons manufacturing processes have been compromised in any way. Tests undertaken by independent laboratories on Dinos & Sons products have proved negative to date for any contaminants, including horse meat."
On Tuesday, authorities raided Peter Boddy slaughterhouse in Todmorden, West Yorkshire, and Farmbox Meats in Llandre in Aberystwyth, West Wales.
Following the release of the FSA results, Environment Secretary Owen Paterson said the food industry has a lot of work to do in the wake of the scandal.
"It's wholly unacceptable that if people buy products marked beef, they turn out to be horsemeat," he said.
"That's why it was so important to undertake this intensive testing activity to gain a meaningful picture. "
More From Sky News