Eggs contaminated with an insecticide called fipronil have been discovered in France, Germany, Belgium, Sweden, Switzerland and Britain, with millions of them pulled off shelves by supermarkets.
The French agriculture ministry said it had also ordered a national enquiry into the egg industry to check for the presence of fipronil, which is used in veterinary products to get rid of fleas, lice and ticks.
The French government says a Belgian company — which it did not identify — mixed fipronil with another, lawful, substance.
Belgium's agriculture minister Denis Ducarme on Wednesday also weighed in on the situation, accusing Dutch authorities of failing to inform their counterparts in the EU about the discovery of fipronil in some eggs last November.
A laboratory assistant investigates eggs. AFP
“When a country like the Netherlands, one of the world's biggest exporters of eggs, does not pass on this kind of information, that is a real problem,” he told a parliament hearing.
The Dutch food and goods watchdog NVWA rejected the claim.
“The allegations that we knew about fipronil in eggs in November 2016 are untrue,” NVWA inspector-general Rob van Lint said in a statement.
However, he admitted his body received an “anonymous tip-off” in November 2016 that fipronil had indeed been used to clean chicken pens in order to combat red lice.
“At that time there was no indication of an acute danger to food safety. There was not a single indication that fipronil could also be present in eggs,” van Lint said.
The European Commission, which oversees the 28-nation European Union's food safety alert system, refused to comment on if and when it was told about the reported Dutch finding.
The insecticide scandal only became public on August 1 when authorities in the Netherlands ordered eggs pulled from supermarket shelves and urged shoppers to throw any they had away.
Germany has meanwhile demanded answers from both countries.
Criminal probes for suspected fraud are under way in Belgium and the Netherlands over the tainted eggs, but prosecutors in both countries have refused to give any details.
Dangerous for consumers?
Fipronil is banned by the EU from being used to treat animals destined for human consumption, such as chickens.
In large quantities, the insecticide is considered by the World Health Organisation to be “moderately hazardous” and can have dangerous effects on people's kidneys, liver and thyroid glands.
The problem is believed to stem from a substance used by a Dutch company, Chickfriend, that farmers in the Netherlands and Belgium say they hired to treat their chickens.
A lawyer for a Belgian company, Poultry-Vision, says the firm sold it to Chickfriend but has not said where it got the substance.