Wholesaler Castell Howell have contacted customers after a 'possible contamination' of cottage pies.
The Food Standards Agency (FSA) has just announced it will extend its UK-wide survey of burgers and similar beef products.
The horsemeat scandal continues to diminish public confidence in the food industry, an ITV News Index poll finds.
Beefburger products made by a mid-Wales firm have been withdrawn after tests revealed the presence of horsemeat.
Three samples of beefburger products made by Builth Wells catering supplier The Burger Manufacturing Company tested positive for at least 1% horsemeat.
The test were requested by the Food Standards Agency and carried out by Powys County Council.
Further tests will now be carried out to establish how much horsemeat the products contain and to test for the presence of the veterinary medicine phenylbutazone.
The FSA said the company is contacting its customers to inform them of the results and to recall any affected products.
Grocery and fresh food supplier Brakes, who supply products containing beef to the House of Commons, has said all four products it was asked to test for horse DNA were negative.
A nursery in the South Wales Valleys and a nursing home in Gwent both bought the cottage pie from Castell Howell wholesalers.
The pie was made by Oak Farm Foods; five customers in total are believed to be affected.
The House of Commons Catering Service has withdrawn four beef products from its outlets that were supplied by grocery and fresh food supplier Brakes.
Brakes is currently carrying out tests on its products containing beef.
"A supplier (Brakes) to the House of Commons Catering Service is currently carrying out tests on its products containing beef," a Commons spokesman said.
"As a precautionary measure, the House of Commons Catering Service has removed from its shelves four beef items supplied by Brakes.
"This relates to meat derivative products rather than to fresh meat provided at the House of Commons.
"Brakes have issued a statement indicating they expect to have completed testing on their own brand beef meat containing products by February 22.
"Tests on two of the four items have been completed so far; both tests have concluded negative for equine DNA."
Food officials have announced they will double the size of their horse DNA tests from 224 to 514 samples across the UK.
Nestle has announced internal testing on its processed beef products sold in the UK and Ireland found "no presence of horse DNA".
The company said it tested samples of seven Jenny Craig products and two Gerber baby food products.
"Nestle UK is part of the industry reporting process and these results will be submitted via the Food and Drink Federation, our industry body, to the FSA [Food Standards Agency] in this week’s reporting cycle", the firm said in a statement today.
"We will continue to test our products in accordance with the FSA’s priorities and the results will be reported to the FSA", Nestle added.
Greencore, the company that supplied Asda with the beef bolognese sauce found to contain 4.8 percent horse DNA, says it is testing for other species in its beef products.