Around 10 countries are so far affected by Europe's spiralling food crisis, in which horsemeat has ended up in millions of ready-to-eat "beef" meals.
The French government has revealed a complex supply chain passing through at least five countries: France, Luxembourg, Romania, the Netherlands and Cyprus.
French anti-fraud office the DGCCRF said on Thursday that food firm Spanghero had knowingly sold 750 tonnes of horsemeat mislabelled as beef over a period of six months, 500 tonnes of which were sent to French firm Comigel, which makes frozen meals at its Tavola factory in Luxembourg.
That meat was used to make 4.5 million products that were sold by Comigel to 28 different companies in 13 European countries.
BRITAIN: In mid-January 2013 horsemeat is found in beefburgers in Britain and Ireland. On February 7, Britain's Food Standards Agency (FSA) announces that lasagne produced by processed food giant Findus contains up to 100 percent horsemeat. Findus UK says that it withdrew the tainted products, supplied by Comigel, in Britain on February 4. On Thursday, police arrest three men working at meat plants on suspicion of fraud. The FSA says on Friday that 29 beef products out of 2,501 tested in Britain have been found to contain more than one percent horsemeat.
FRANCE: On Tuesday, France becomes the second European country to confirm the presence of horsemeat in frozen meals. Its supermarkets pull ready-made meals from the shelves as a precaution. Comigel says it has withdrawn all products from Spanghero, which says that the meat comes from Romania. On February 14, the DGCCRF anti-fraud office pins most of the blame on Spanghero.
SWEDEN: The authorities say they will carry out DNA tests on meat in ready-made meals sold in supermarkets after Findus finds horsemeat in its products. Swedish retailers pull six different brands of ready-to-eat lasagne meals, all made by Comigel.
GERMANY: On Thursday, supermarket chain Real says it has found traces of horsemeat in frozen lasagne that it had already pulled as a precautionary measure off the shelves. Supermarket chains Edeka, Kaiser's Tengelmann and frozen goods chain Eismann are also testing their products.
SWITZERLAND: Swiss supermarket giant Coop says on Wednesday it has found horsemeat in its own-brand frozen lasagne produced by Comigel, a day after announcing it was withdrawing all Comigel-produced lasagne as a precautionary measure.
THE NETHERLANDS: On Monday, the Dutch food and consumer watchdog opens a probe to see whether any beef products stocked on shelves contain horsemeat, searching and carrying out tests at around 100 businesses. Dutch officials on Friday raid a meat processing plant in the south of the Netherlands believed to be mixing horsemeat and beef and selling it on as pure beef.
NORWAY: On Friday three big Norwegian food retailers say that horsemeat has been found in frozen lasagne dishes that had already been withdrawn from store shelves.
DENMARK: Food safety authorities on Friday probe whether a slaughterhouse may have mixed horsemeat into meat marked as beef that was supplied to pizza makers.
AUSTRIA: A beef tortelloni dish distributed by German chain Lidl is pulled from the shelves on Friday after Austria's food safety agency said traces of horsemeat were found in the product.