* Ministers to meet on Wednesday to debate response
* EU health chief says all firms involved under suspicion
* Germany testing meat consignment
By Charlie Dunmore
BRUSSELS, Feb 13 (Reuters) - European countries are expected to step up testing of food products in response to a scandal involving horsemeat falsely sold as beef, as authorities scramble to identify the source of the suspected fraud.
All companies that have handled falsely-labelled horsemeat are under suspicion, the European Union's health chief said on Wednesday, adding that the European Commission was considering strengthening EU rules on product labelling.
Ministers from the worst-affected nations will meet in Brussels later on Wednesday to discuss their response to the scandal, which erupted after tests showed products labelled as beef contained up to 100 percent horsemeat.
Authorities have said there is no risk to public health from the tainted foods. But the incident has caused revulsion in Britain, where many view the idea of eating horsemeat with distaste, and raised concerns over the safety of Europe's intricate food supply chains.
"It is evident that somewhere down the line, someone ... has fraudulently or perhaps negligently labelled a product in a deceptive way," EU health commissioner Tonio Borg told reporters.
"All those countries through which this meat product has passed of course are under suspicion. By the countries, I mean the companies in those countries which dealt with this meat product," he said, adding it would be unfair at this stage to point the finger at any organisation in particular.
Wednesday's meeting would focus on strengthening existing EU rules, particularly on product testing and enforcement by national authorities, Borg said.
Britain's finance minister George Osborne said tougher product testing was needed to restore public confidence.
"What we want to make sure is that we have got the right checks in place so that all families know exactly what they are eating," he told Sky TV.
The Commission said it was also studying the option of introducing country-of-origin labels on processed meat products, although officials have said privately that the complexity of supply chains would make this next to impossible to implement.
NOT JUST HORSE?
On Jan. 15 routine tests by Ireland's Food Safety Authority found horsemeat in frozen beef burgers produced by firms in Ireland and Britain and sold in supermarket chains including Tesco, Britain's biggest retailer.
Concerns grew last week when the British unit of frozen foods group Findus began recalling packets of beef lasagna on advice from its French supplier Comigel, after tests showed up to 100 percent of the meat in them was horse.
The affair has since implicated operators and middlemen in a host of EU countries, from abattoirs in Romania and factories in Luxembourg to traders in Cyprus and food companies in France.
Germany said it was investigating a consignment of beef lasagna sent from Luxembourg to an unnamed retailer in North Rhine-Westphalia on suspicion it might contain horsemeat.
The first evidence that the labelling scandal could go beyond horsemeat also emerged, as upmarket British grocer Waitrose said its testing found that some of its frozen British beef meatballs might contain pork.
The firm, part of the John Lewis Partnership, has withdrawn the product from sale.