LONDON (AP) -- Britain's police and food safety regulator on Tuesday raided a slaughterhouse and a meat processing firm suspected of selling horsemeat labeled as beef for kebabs and burgers.

The Food Standards Agency said it shut down the Peter Boddy slaughterhouse in northern England and Farmbox Meats in west Wales, which it supplied.

The growing scandal over horsemeat mislabeled as beef in frozen processed food has led to supermarkets in a growing number of European countries pulling meals from their shelves.

Horsemeat is largely taboo in Britain and Ireland, though in France it is sold in specialty butcher shops. While no health effects have been reported, the scandal has unsettled consumers and made clear that someone in the complicated network of meat wholesalers is benefiting from selling much cheaper horsemeat as beef.

The British food safety agency said it seized all meat found at the premises of the two companies, and that it was investigating how "meat products, purporting to be beef for kebabs and burgers, were sold when they were in fact horse."

Agency director Andrew Rhodes said this appeared to be a case of "blatant misleading of customers."

"This is absolutely shocking. It's totally unacceptable if any business in the U.K. is defrauding the public by passing off horsemeat as beef," Environment Secretary Owen Patterson said.

It was not immediately clear where and how far the horsemeat products were distributed.

The move comes after recalls of burgers, frozen lasagna and other pre-prepared meals in several European countries. France says Romanian butchers and Dutch and Cypriot traders were part of a supply chain that brought horsemeat to some supermarket shelves.

Romanian food safety officials said Tuesday that the country produced 6,300 tons of horse, mule and donkey meat last year, and that it was correctly labeled when it was exported from 35 authorized plants to other European countries. Officials have said the fraud occurred somewhere else down the line.

In rural Romania, horses are sold from individual households to abattoirs, and each animal has four sets of documents before the meat is exported.

The manager of a Romanian slaughterhouse implicated in the scandal, Doly Com, defended his plant on Tuesday and tried to assuage buyers' concerns about his company's meat.

"We have always watched closely the way we work here....and we can guarantee one hundred percent that all the products Doly Com puts on the market are certified from a quality and origin point of view. One hundred percent," said Iulian Cazacut, the plant's general manager, where horsemeat accounts for just five percent of the plant's business.

No horse was being processed Tuesday in the plant in remote northeast Romania. Dressed in white overalls, their heads and mouths hygienically covered, workers pierced cow and pork carcasses with sharp knives, sawing off hunks.

The other Romanian slaughterhouse implicated in the horsemeat scandal, Carmolimp, has also denied wrongdoing.

Sweden's food safety authority said it would test a wide range of frozen meat products sold in supermarkets to check whether they contain horsemeat and have been mislabeled.

Peter Bradenmark, head of food control management at Sweden's National Food Agency, told the AP that the agency would test about 50 to 100 samples from supermarkets nationwide.

"What's happened is alarming," he said. "Food companies are sincere and they want to do the right thing. But sometimes things go wrong unintentionally, and unfortunately, at times it's intentional."

Associated Press writer Nicolae Dumitrache contributed to this story from Roma, Romania.