The Food Standards Agency has told the food industry to share the results of product tests, which look for horse DNA down to a level of one per cent, with the aim of increasing consumer confidence.
Lancashire schools were among those affected last week when horse meat was found in some of the frozen meals heading for the dinner tables.
Nearly 50 schools had food withdrawn from the canteens when cottage pies testing positive for horse DNA sent to 47 Lancashire schools had to be withdrawn.
The FSA said this week that its own tests for horse meat in processed meat products were being expanded to ensure a wide range of products was sampled.
The first phase of tests concentrated on samples of minced beef products being checked for horse and pork DNA, while the second phase involved samples of beef-based ready meals.
Results of the industry tests on 2,501 beef products collated by the FSA last week revealed 29 positive results on foodstuffs ranging from frozen beef lasagne and spaghetti bolognese, Co-op frozen quarter-pounder burgers
Pub and hotel group Whitbread has also pulled lasagne and burgers from its menus after admitting horse DNA had been found in its food.
The third phase will include products marketed or labelled as containing beef as a major ingredient. Products including gelatine, beef dripping, stock cubes, steak, stewing steak as well as ready meals which contain beef that is not minced are included. Testing on the third phase is due to begin next week.