"AFSCA and its laboratories are now conducting research in order to explain the difference in results and the agency hopes to receive clarifications at the soonest possible moment", the watchdog said in a statement, adding that the eggs in question had been blocked from shops since July 18 and, therefore, did not pose a risk to consumers.
In the netherlands, the agency for food security (NVWA) has, however, explained that some batches of eggs exhibited a rate of fipronil " so high that their consumption poses a serious danger to public health ".
The Food Standards Agency says it is investigating how eggs that may have been contaminated with a toxic insecticide ended up on United Kingdom supermarket shelves.
About 0.0001% of eggs imported into the United Kingdom each year were contaminated with the insecticide, the food safety watchdog said on August 7.
The product is thought to have been used "inappropriately" as a cleaning product on some European Union farms, despite not being authorised for use as a veterinary medicine or pesticide around food-producing animals.
Fipronil is a common ingredient in veterinary products for getting rid of fleas, lice and ticks in animals.
A very small number of eggs contaminated with a toxic insecticide reached the United Kingdom earlier this year.
The latest news comes just a day after the UK's Food Standards Agency revealed that a "very small number" of potentially contaminated European eggs have entered the United Kingdom, .
Investigators in the Netherlands believe the insecticide was illegitimately used in a cleaning product, made by a Belgian company, used to treat red mite in poultry houses. It said it had not commented because of an ongoing judicial investigation.
"It is criminal, that is very clear", Christian Schmidt told German television station ARD on Tuesday.
Belgium authorities admitted only after the scandal reached crisis proportions that they were aware in early June of 'a problem in the poultry industry with fipronil, ' according to news reports.
"The Food Standards Agency is committed to making sure that food is safe". 'We kept it a secret for the course of the investigation'.
In the statement, the minister added: "The presence of traces of fipronil is not, in itself, a risk". 'As it stands the situation is a risk management issue, which is being dealt by the competent authorities at national level'.