The assurances followed yesterday's announcements that horsemeat had been found in schools, hospitals and one of the country's largest pub and hotel chains as the scandal over food fraud continued.
Despite the assurances, one Westcountry school took Cornish pasties off the menu "as a precautionary measure" as fears over contaminated food showed little sign of easing.
The disclosure came as a total of 29 of the 2,501 items tested by the food industry, which reported to the Food Standards Agency, tested positive for horsemeat, covering seven different products. Retailers, who have been criticised by Downing Street for adopting a low profile during the crisis, hailed the fact 99% of tests came back negative.
Meanwhile, pub and hotel group Whitbread – which owns Premier Inn, Beefeater Grill and Brewers Fayre – admitted horse DNA had been found in its food, and took meat lasagnes and beefburgers off its menus.
And it was confirmed that cottage pie testing positive for horsemeat was delivered to school kitchens in Lancashire, while officials revealed burgers containing horsemeat had been supplied to hospitals in Northern Ireland.
In Cornwall, Richard Lander School in Truro said pasties, beef pasta sauces and beef used in baguettes had all been withdrawn. The school said almost all of the food it offered was provided by Eden Foodservices and used British Red Tractor produce, which is fully traceable with guaranteed welfare standards. But the school was also buying in other food which did not fall under Red Tractor.
Steve Mulcahy, headteacher at the secondary school, said in a memo to parents: "These products will be temporarily withdrawn purely as a precautionary measure until they can confirm with 100% certainty the traceability of these products."
School catering contractors are invariably decided by individual schools. Education authorities across Devon and Cornwall moved to reassure parents of pupils at schools it controls that meals supplied by third parties were not contaminated.
Cornwall Council has a contract with private firm Chartwells to supply meals to 197 schools.
A council spokesman said: "The authority takes the health and wellbeing of children in Cornwall extremely seriously and immediately contacted the company to seek reassurances.
"The company has confirmed that all its nominated suppliers have to meet strict food quality and safety standards and they regularly undergo independent audits to ensure these standards are upheld."
Torbay Council said Eden Foodservices also supplied the majority of its primary schools. A council spokesman said it had been "assured" by the company it was "confident that no contamination has occurred in any of its beef products", adding: "This is a result of robust due diligence processes it has in place with its suppliers."
A spokesman for Devon County Council said: "Schools make their own catering arrangements, but those which have chosen to use Devon Norse, the council's catering supplier, have been given assurances that its meat products have full traceability and are sourced locally.
"Norse's beef burgers are either home-made using locally sourced Westcountry beef or made especially for them using the same high-quality ingredients."
The council added its trading standards team is carrying out its own investigations into meat products supplied in Devon.
A Plymouth City Council spokesman said it provided catering for the majority of the city's schools, community meals and residential homes.
She said: "Our meat supplier for our school meals and residential home catering provides us with locally sourced produce from two companies within the South West where the meat is farmed on their premises. These companies have issued written assurances to our supplier that they provide 100 per cent beef."
She added that tests conducted have so far shown meat not to be contaminated.
In the Commons on Thursday, Devon MP Neil Parish called for a debate on food labelling for processed meals.
He said: "The horse scandal has shown that the labels on processed food throw mystery on where that food comes from, rather than provide enlightenment.
"We have an opportunity to get something positive from this scandal, by making sure that people recognise where their food comes from."
