The French government has accused wholesalers in Europe of overlooking clear indications that the meat they purchased from other traders was horse meat mislabelled as beef, in a scandal that has led to investigations across the continent.
Authorities said on Thursday that the price, smell and colour of the meat should have been blatant tip-offs that the products were falsely marketed.
Benoit Hamon, the country's consumer affairs minister, pinned the bulk of the blame on Spanghero, a French wholesaler, at the heart of the growing scandal, which has reached across 13 countries and 28 companies in Europe.
He said there was plenty of blame to go around, but most of it rested with Spanghero, which is based in southern France.
Officials at Spanghero denied knowingly buying and reselling horse meat but French authorities immediately suspended their trading activities.
Hamon said Spanghero was one company in a chain that started with two Romanian slaughterhouses that says they clearly labelled their meat as horse.
The meat was then bought by a Cyprus-registered trader and sent to a warehouse in the Netherlands.
Spanghero bought the meat from the trader, then resold it to the French frozen food processor Comigel.
The resulting food was marketed under the Sweden-based Findus brand as lasagna and other products as containing ground beef.
Hamon said Spanghero was well aware that the meat was mislabelled when it sold it to Comigel.
"Spanghero knew,'' Hamon said. "One thing that should have attracted Spanghero's attention? The price.''
Hamon said the meat from Romania cost far below the market rate for beef.
A representative for Spanghero said company officials have been interrogated by authorities, who have raided Spanghero headquarters several times in recent days, but no one has been arrested.
The representative insisted the company acted "in good faith" and that it never knew the meat it bought and sold was horse meat.
Food processor Comigel was not blameless either, Hamon said, declaring that the paperwork from Spanghero had significant irregularities, including a failure to specify country of origin.
"And once the meat was defrosted, we can ask ourselves why Comigel didn't notice that the colour and odour was not that of beef?'' Hamon said.
Romanian food suppliers rejoiced that the blame for the frozen lasagna scandal has shifted away from Romanian slaughterhouses to companies in France.
Sorin Minea, the chief of Romalimenta, the Romanian food industry association, urged tough sanctions for the French companies.
"Romania, small and ugly as it is, respected all European legislation. In the UK, legislation was not respected," he said.
"I am sad that first we were accused and then there was an inquiry. We feel we are not part of the European family.''
Police in the UK, meanwhile, announced the arrests Thursday of three men on suspicion of fraud at two meat plants inspected earlier this week by the country's Food Standards Agency.
Europol, the European Union police agency, is coordinating a broad continent-wide fraud investigation amid allegations of an international criminal conspiracy to substitute horse for more expensive beef.