PARIS -- France will press all of Europe to impose strict labeling rules on the meat inside prepared foods to restore confidence that has been shaken by a widening scandal on horse meat that was mislabeled and cooked into frozen dinners, the president said Saturday.

Three major French food companies, including one at the heart of the horse meat furor, agreed over the past two days to use only French beef in the prepared meals they sell in the country. Italy on Saturday registered its first case, with horse DNA discovered in pre-packaged lasagna from a Bologna-based food-maker, Primia. The meat was in the bolognese sauce.

The horse meat scandal began with tons of horse meat from Romanian abattoirs exported to France, where it was processed into ready-made meals. Romanian authorities said the meat was correctly labeled as horse and that the fraud occurred further down the food supply chain.

Since then, horse meat has turned up across Europe in frozen supermarket meals and in restaurants, schools and hospitals.

Under current European rules, companies are supposed to indicate the kind of meat in prepared foods, but not its origins. President Francois Hollande, speaking at the French Agricultural Salon, said he expected it would take several months to persuade other countries to go along with the rule change.

The fraud was possible "because there wasn't labeling," Hollande said. "Consumers should be able to know the provenance of the products they consume, especially for meats."

The French frozen food manufacturer Findus was among the first companies to acknowledge the mislabeled horse meat, which was shipped from country to country before finding its way into prepared foods. Findus and grocery chains Carrefour and Intermarche said they would now use French beef exclusively in prepared foods for consumers.