The local sanitary unit of the northern city of Mantova identified the dioxin-polluted eggs during an inspection in local farms lying close to industrial plants, from where the contamination originally set off.

The authorities have sealed the areas and placed a ban on both consumption and commerce of the eggs to nearby shops. According to local media, the farmers are all small breeders who keep their animals out in the open.

Leading consumer association Federconsumatori launched an alarm, saying what happened was extremely serious and dangerous and posed a threat to food safety.

"This is why we demand that regular controls be intensified for the benefit of consumers' health," said Federconsumatori's President Rosario Trefiletti.

It's not the first time food safety in Italy is endangered by elevated dioxin levels. In 2006 excessive dioxin coming from waste treatment plants near Naples contaminated the famous Mozzarella cheese, while recently there have several cases of polluted sheep milk.