Supermarkets in Germany, the Netherlands, Belgium, Sweden and Switzerland have pulled millions of eggs from the shelves after fipronil, a substance potentially dangerous to humans, was found in them.
Dutch farming organisation LTO said that several million hens may need to be culled at 150 companies in the country, with 300,000 having already been killed.
An LTO spokesman said late Sunday that they "had to be eliminated because of contamination".
Denis Ducarme said in a statement he had told the food safety agency (AFSCA) to produce a "report on the circumstances of the agency's actions since the first information it received about the fipronil problem"
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Facing pressure from Germany and the Netherlands, Ducarme promised "complete transparency".
He said he would speak by telephone with his counterparts in the coming days.
Ducarme added that products from 57 Belgian egg producers -- around a quarter of the country's -- had been blocked as a preventative measure.
European Commission spokeswoman Anna-Kaisa Itkonen said she could not comment on the Belgian delay "because it's an ongoing criminal investigation."
Germany has demanded an explanation from Belgium about why the issue was kept covered up.
Fipronil is commonly used in veterinary products to get rid of fleas, lice and ticks. But it is banned from being used to treat animals destined for human consumption, such as chickens.
In large quantities, the insecticide is considered to be "moderately hazardous" according to the World Health Organization, and can have dangerous effects on people's kidneys, liver and thyroid glands.
Dutch and Belgian media reports that the substance containing the insecticide was supplied to Chickfriend by a Belgian firm have not been confirmed.