Sodexo has withdrawn all frozen beef products after tests found equine DNA in some beef burgers, minced beef and halal minced beef.
The results were part of the second set of tests published by the Food Standards Agency.
In total 3,634 products have been tested by 132 food suppliers, of which 35 tested positive for horse. No samples have been found to contain the veterinary medicine phenylbutazone (bute).
So far caterers and wholesalers have completed 80% of tests. Another update will be published next Friday.
In a statement Sodexo said: "We demanded written assurances from across our supply chain that the products we purchase did not contain horse meat, and additionally implemented an internal sampling programme. Despite repeated guarantees from our suppliers, our sampling has identified a frozen beef product which tested positive for equine DNA. This situation is totally unacceptable.
"We felt the only appropriate response was to withdraw not only this product but all frozen beef products. We will only re-admit into our catering operations products that have affirmatively passed DNA testing, pursuant to laboratory test criteria."
It added that its Tillery Valley Foods business, which provides meals to the healthcare sector, was not affected.
Other products reported by the FSA to contain horse DNA included lasagne and beef burgers from Whitbread and ASDA chilled beef bolognese sauce.
FSA chief executive Catherine Brown said: "The overwhelming majority of results, over 99%, have come back negative for the presence of horse DNA above the threshold of 1% - which is reassuring for consumers.
"However, our work is far from done. The sampling programme being carried out by local authorities on behalf of the FSA is already well under way and we expect to report the initial findings from that work in early March.
"We are also committed to pursuing enforcement action where we can, to ensure that those who were at fault take full responsibility for their actions. We are determined to get to the bottom of this to find out exactly what happened - and to make sure it doesn't happen again."
Catering supplier's burgers test positive for horse meat >>