British food safety authorities say about 1% of the beef products they have tested so far contain horse meat.
The Food Standards Agency (FSA) tested 2,501 products and found 29 contained horse meat.
The products included lasagne, spaghetti bolognese and burgers sold in supermarkets. All have already been withdrawn from sale, the ABC reports.
Testing covered only one-quarter of the entire range of available products, and did not look for contamination of less than 1%.
"The overwhelming majority of beef products in this country do not contain horse," FSA chief Catherine Brown said.
"The examples we have had are totally unacceptable, but they are the exceptions."
Separate tests confirmed horse meat was delivered in meals to dozens of schools.
Cottage pie testing positive for horse DNA was sent to 47 Lancashire schools.
More results are expected next week.
Meanwhile, the European Union has agreed to start testing food products for horse DNA and phenylbutazone, or bute, a banned horse painkiller not meant for human consumption.
Concerns about horse meat first emerged in mid-January when Irish authorities found traces of horse in beef burgers made by firms in the Ireland and Britain and the UK and sold in supermarket chains, including Tesco and Aldi.
The discovery has sparked a European crisis, with supermarkets across the continent withdrawing millions of beef products.