FILE PHOTO: Eggs are packed to be sold at a poultry farm in Wortel near Antwerp, Belgium August 8, 2017. REUTERS/Francois Lenoir

FRANKFURT (Reuters) - Eggs contaminated with the insecticide fipronil have been discovered in 40 countries, including 24 of the European Union’s 28 member states, German news agency DPA reported on Tuesday, without citing its sources.

Millions of eggs have been pulled from European supermarket shelves, though some national regulators have voiced concern that many contaminated eggs have already entered the food chain, mainly through processed products such as biscuits, cakes and salads.

EU agriculture ministers meeting in Tallinn, Estonia, are due to discuss the egg scandal on Tuesday, DPA said.

DPA said a spokeswoman for the European Commission confirmed that the only EU member states so far unaffected are Lithuania, Portugal, Cyprus and Croatia.

The non-EU states in which contaminated eggs have been discovered include the United States, Russia, South Africa and Turkey, DPA reported.

Dutch and Belgian authorities traced the source of the insecticide to a supplier of cleaning products in the Netherlands. Two Dutch men who ran the cleaning company Chickfriend were arrested last month.

While a large number of contaminated eggs would need to be eaten to affect health, fipronil is considered moderately toxic and can cause organ damage in humans.

It is widely used to treat pets for ticks and fleas but its use in the food chain - for example, to clean out barns - is forbidden.