Cottage pie that was delivered to 47 schools in Lancashire has tested positive for horse DNA.
The product has now been withdrawn from kitchens.
Officials at Lancashire County Council say the amount of horse consumed by the children will have been 'minute.'
Analysts at one of six laboratories in the country doing the FSA's tests discovered the contaminated product late yesterday.
Scientists uncovered equine DNA at 0.1% concentration in samples.
Headteachers have been alerted.