Birds Eye has withdrawn three beef ready meals from supermarkets in the UK and Ireland as a precaution after horse DNA was found in a product in Belgium.
Birds Eye said its chilli con carne had tested positive for 2% horse DNA.
Meanwhile, the Food Standards Agency (FSA) has announced results from 1,133 new tests on beef products.
There were six positive tests for horse DNA at a level of greater than 1% - all on products which have been withdrawn.
The tests covered a range of frozen, chilled or canned products that included lasagne, chilli con carne, cottage pie, ravioli, cannelloni and spaghetti bolognese.
UK food suppliers have now carried out a total of 3,634 tests, the FSA said, and more than 99% had come back negative.
However, 35 results, representing 13 products, contained 1% or more horse DNA.
They had all been previously identified and withdrawn from shelves with the exception of beef burgers, minced beef and halal minced beef from Sodexo, a French catering and facilities giant.
In the UK, Sodexo supplies food to schools and colleges, hospitals and via "meals on wheels", as well as running four prisons.
Though the company said it had withdrawn the relevant products, it would not give details of public sector institutions it supplied.
Food firms have also been testing products for the veterinary medicine bute (phenylbutazone).
The medicine can be dangerous to humans because in rare cases it causes a serious blood disorder known as aplastic anaemia. While the FSA insists there is a low risk to health, bute is not allowed to enter the food chain.
- In Scotland, councils have been told not to use any frozen beef products following the discovery of horse DNA in a burger at Cumbernauld High School in North Lanarkshire.
- In Wales, the Local Government Association said testing for horsemeat would be "ratcheted up" after food supplied to seven councils tested positive
On Thursday, a Department for Environment, Food and Rural Affairs (Defra) statement reported a "productive" meeting with industry leaders over the use of horse passports.
It said: "Everyone agreed that the steps already taken have eliminated the risk of horses containing bute from entering the food chain.
"We are pleased that the sector agreed the need to tighten and investigate ways to improve the horse passport system.
"We welcome the commitment of the sector to develop their own equine database."
Although Birds Eye's chilli meal is only sold in Belgium, the company said it would withdraw all other products made by the supplier - Belgian group Frigilunch.
The company said as a precautionary measure in the UK and Ireland it would clear its Traditional Spaghetti Bolognese 340g, Shepherd's Pie 400g and Beef Lasagne 400g from the supermarkets. It will also clear the chilli from shelves in Belgium.
Birds Eye said: "Whilst this is not a food safety issue, it is clearly unacceptable."
"We want to reassure you from the testing we have completed that all Birds Eye beef burgers, beef pies and beef platters do not contain horse DNA."
Customers who have bought any of the three products will be offered a refund if they contact Birds Eye customer services, the group said.
"We want to apologise to consumers and reassure them that we will keep them fully informed and that we are taking action to deal with this issue," the company added in a statement.
Birds Eye is the latest in a growing number of companies, including Findus and Nestle, to recall beef ready meals.
Last month's discovery of horsemeat in some processed beef products sold by a number of UK supermarkets has sparked widespread investigations.
The FSA asked UK food retailers to test the beef in thousands of their products. In the first results, released on 15 February, 29 out of 2,501 tests were positive - that is, they contained at least 1% horsemeat.