It said 212 out of 224 samples on minced beef-based products had tested negative.
Horsemeat has been found in minced beef served at schools in Leicestershire, the county council has confirmed.
The firm said it had issued a notice withdrawing frozen minced beef produced from 12 December to 17 January.
Newport-based Welsh Bros Food contacted Sandwell Council on Wednesday to report one batch of frozen minced beef had "potentially tested positive".
Northamptonshire County Council said it took the precautionary measure when horsemeat was detected in one of 10 tests on frozen minced beef.
The BRC says 95% of its members' products have been checked, including all minced beef lines used by the UK's largest supermarkets.
The Co-Operative Group said 59 of its 102 own-brand minced beef products have been tested so far, with all found to be clear of horsemeat.
The employee failed to wash her hands after touching raw minced beef and claimed cooked ham had a shelf life of up to six days.
But minced horse and minced beef look very similar, says Bedington.
The FSA has requested that local authorities test minced beef products and ready meals sold at shops, wholesalers and catering suppliers for horse and pig DNA above a 1% threshold.
Birds Eye said they were introducing a "triple lock" DNA testing programme which means no minced beef product can reach the supermarket shelf without have been cleared at three stages of DNA testing.
In addition to the Creative Foods lasagne, the parent firm said another of its Brakes' products, a spicy minced beef skewer had tested positive for horse DNA at between 1% and 10% levels.
BBC: Horsemeat scandal: Creative Foods lasagne test positive
In response to the horsemeat scandal, the FSA requested that local authorities test minced beef products and ready meals sold at shops, wholesalers and catering suppliers for horse and pig DNA above a 1% threshold.
This was a hard slab of salted, minced and sometimes smoked beef mixed with onions and breadcrumbs.
The first book featured family standards like Zippy Olive Beef Spread, made by combining whatever wine is on hand, instant minced onions, cream cheese, mayonnaise, chopped cocktail olives and beef cut up with kitchen shears.
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