LONDON (AP) -- The European Union agreed Friday to begin random DNA checks on meat products in a bid to put a lid on a spreading scandal over horsemeat, while British authorities announced traces of horse had been found in school meals, restaurant dishes and hospital food, as well as supermarket products.
A rundown on a scandal that continues to spread:
WHERE DID EUROPE'S HORSEMEAT SCANDAL BEGIN?
In mid-January, Ireland's food safety watchdog announced that it had discovered traces of horse DNA in burger products sold by major British and Irish supermarkets.
The mislabeled products came from Irish processor Silvercrest Foods, which withdrew 10 million burgers from store shelves.
Irish officials first blamed an imported powdered beef-protein additive used to pad out cheap burgers, then frozen blocks of slaughterhouse leftovers imported from Poland -- an indication of the complexity of the food-supply chain that was about to be revealed to an alarmed European public.
WHERE ELSE HAS HORSEMEAT BEEN FOUND?
Traces of horsemeat have turned up across Europe in frozen supermarket meals such as burgers and lasagna, as well as in in fresh beef pasta sauce, on restaurant menus, in school lunches and in hospital meals.
Millions of products were pulled from store shelves in Britain, Ireland, France, Spain, Germany, Denmark, Sweden and Norway after the scandal broke, and supermarkets and food suppliers were told to test processed beef products for horse DNA.
On Friday, several British supermarket chains -- including Morrisons and Tesco -- said their tests had been negative so far. But Britain's Food Standards Agency said 29 of 2,501 products tested contained at least 1 percent horse DNA. All were burgers, lasagna and meat sauces sold by supermarkets and catering firms.
The scandal has also spread beyond supermarket foods. Whitbread PLC, Britain's largest hotel and restaurant company, said Friday that horse DNA had been found in lasagna and burgers on menus at its outlets including Premier Inn hotels and Brewers Fayre and Beefeater Grill restaurants. Whitbread said it was "shocked and disappointed at this failure of the processed meat supply chain."
Officials also said horsemeat was present in cottage pies delivered to 47 schools in Lancashire county, northern England, and in hospital meals in Northern Ireland.
Tests are continuing, and officials say this is far from over.
"The more people have looked for horsemeat, the more products have been found containing it," said Duncan Campbell, a senior British food inspector. "I don't think we have got to the bottom of it yet."
HOW DID THE HORSEMEAT GET THERE?
European officials say the scandal is the result of fraud, and possibly an international criminal conspiracy to pass off cheap horsemeat as more expensive beef.
The French government says the chain of fraudulent meat sales reaches across 28 firms in 13 countries.
At least some of the horsemeat originated at abattoirs in Romania, and was sent through a Cyprus-registered trader to a warehouse in the Netherlands. A French meat wholesaler, Spanghero, bought the meat from the trader, then resold it to the French frozen food processor Comigel. The resulting food was marketed in Britain and other countries under the Sweden-based Findus label as lasagna and other products containing ground beef.
French authorities blame Spanghero for the fraud, but it strongly denies wrongdoing.
"The responsibility started upstream," chief executive Barthelemy Aguerre said Friday. "We didn't want to cheat anyone."
The Romanian companies and the Dutch trader also deny fraud. They say the meat was clearly labeled as horse when they handled it.
Dutch prosecutors said Friday that food safety experts raided a meat processing plant as part of a criminal investigation into horsemeat fraud. Prosecutors said the company in North Brabant province is suspected of fraud and money laundering. The company -- which was not named, in line with Dutch privacy laws -- is believed to have processed horsemeat from the Netherlands and Ireland, and mixed it with beef before selling the mixture as "pure" beef.
Separately, British authorities have raided five businesses -- including an English slaughterhouse and a Welsh meat processor -- on suspicion of passing off horsemeat as beef in burgers and kebabs. Three men have been arrested.
IS IT DANGEROUS?
Horsemeat itself is not harmful, and is eaten in several European countries, including France, Germany and Italy. In English-speaking countries including Britain and Ireland eating horses is widely considered taboo.
British officials have said that horses slaughtered in Britain after being treated with the equine painkiller phenylbutazone, or bute, may have made their way into the human food chain in France. Bute is banned for human use because in rare cases it causes severe side effects, but veterinary experts say there is little risk from consuming small amounts in horsemeat.