Revelations that some beef dishes actually contained horsemeat has caused a scandal across Europe, leading to products being removed from sale and police investigations.

It has also cast a spotlight on food labelling and the complex supply chain across the EU trading bloc, damaging Europeans' confidence in the food on their plate and putting pressure on governments to explain lapses in quality control.

An investigation into activities at meat-processing firm Spanghero has revealed "serious, specific and coherent" reasons to suspect it knowingly defrauded customers and consumers by selling them horsemeat labelled as beef, the government said.

However, the firm's 330 workers were not to blame and would meet with Agriculture Minister Stephane Le Foll on Monday to determine how they would be paid until the plant, whose sanitary license has been revoked temporarily, could reopen.

"The government distinguishes responsibility for what appears to be the actions of Spanghero's leaders from the work of its employees," ministers for agriculture and consumer affairs said in a joint statement.

The scandal, affecting a growing number of European countries and retailers, began in Ireland when its food safety authority discovered horsemeat in frozen beef burgers.

Investigations to determine how horsemeat ended up in ready meals sold across Europe homed in on Spanghero, but further probes are under way targeting a meat trader in the Netherlands and other firms in the supply chain.