The investigation is being done by Dutch food safety authority NVWA's investigative department, on behalf of the Public Prosecutor.
In large quantities, the insecticide is considered to be "moderately hazardous" according to the World Health Organization, and can have risky effects on people's kidneys, liver and thyroid glands.
"And as the authorities in Belgium and Holland get more information they pass that onto our own Food Standards Agency".
Fipronil is a widely-used anti-lice agent used to spray farm animals, is absorbed into the skin, and passes into hatched eggs.
The scandal also spread eastwards on Thursday as a tonne of contaminated egg yolk was found in Romania, and 21 boxes of the tainted eggs were discovered in Slovakia.
What is being done about it?
"It is very unlikely that these eggs pose a risk to public health, but as Fipronil is unauthorized for use in food-producing animals we have acted with urgency to ensure that consumers are protected", it said.
The FSA said investigations into the incident suggested it was "very unlikely" that the eggs posed a risk to public health as it released a list of processed products withdrawn in the United Kingdom "to ensure that consumers are protected".
Numerous eggs were mixed with others which had not come from affected farms so Fipronil residues would be highly diluted, the FSA said.
"Blaming and shaming will bring us nowhere and I want to stop this", Mr Andriukaitis, the Lithuanian commissioner, said.
The European Commission said it only learned about the contamination in late July after receiving an official notification from Belgium. It is unclear whether the meeting will involve all 28 European Union member states, or only affected countries.
Dutch police have arrested two people suspected of using fipronil.
Why have countries been arguing?
Korea has banned the distribution and sale of imported products with processed eggs from Belgium, Germany and the Netherlands, which are convulsed by a contamination scandal.
Last week, media reported that Aldi and Lidl supermarkets in Germany recalled millions of eggs from shelves over fears that they might have been contaminated with fipronil.