Polish authorities said Friday they had discovered around 40,000 insecticide-tainted eggs imported from EU neighbour Germany, but gave assurances that none had made it to supermarket shelves.
"The eggs did not reach consumers and will be destroyed or returned to their German supplier," Poland's Chief Sanitary Inspectorate said in a statement.
Polish authorities were informed about the fipronil-tainted eggs by an EU-wide rapid alert system, the inspectorate's statement said.
On Thursday, Slovak veterinary inspectors found 21 packages of hard-boiled and peeled eggs that were contaminated with fipronil in a warehouse of the western village of Vrbove, agriculture ministry spokeswoman Zuzana Peiger Acjakova told AFP.
Fipronil is commonly used to get rid of fleas, lice and ticks from animals but is banned by the EU from use in the food industry. It can harm people's kidneys, liver and thyroid glands.
The problem is believed to stem from a substance used by Dutch company Chickfriend which farmers in the Netherlands and Belgium say they hired to treat their chickens.
The eggs at the centre of the scandal have mainly come from the Netherlands, followed by Belgium and Germany. Scores of farms have been shut.
The European Commission said Friday that tainted eggs from European poultry farms had been found in Hong Kong and Switzerland as well as 15 EU countries.