Around 700,000 eggs in the UK have been implicated in the European egg contamination scandal, the Food Standards Agency has revealed.
Earlier in the week, the FSA said that the number was only 21,000 but after further tests and inspections the number has been revised up significantly.
A number of products are affected including processed foods such as sandwich fillings which uses eggs as well as other chilled products.
In a statement, the FSA said: "Investigations into the Fipronil incident in Europe continue. We have now established that more eggs from affected farms than previously identified came to the UK.
"It is very unlikely that these eggs pose a risk to public health, but as Fipronil is unauthorised for use in food-producing animals we have acted with urgency to ensure that consumers are protected."
In large quantities, Fipronil is "moderately hazardous" according to the World Health Organisation with an impact on kidneys, liver and thyroids.
However the risk is deemed to be low according to the FSA, however the pesticide is banned for use in animals that produce food.
Heather Hancock, Chairman of the Food Standards Agency, said: "I'm confident that acting quickly is the right thing to do.
"The number of eggs involved is small in proportion to the number of eggs we eat, and it is very unlikely that there is a risk to public health.
Millions of eggs have been taken off shelves in Europe already with Aldi and Lidl pulling lines of eggs in Germany.
In the Netherlands where bulk of the contaminated eggs have come from, millions of hens are set to be culled to prevent the spread of the pesticide.
Despite the concerns, 85% of all eggs consumed in the UK are also laid here too, and the FSA stressed that no evidence of Fipronil had been found in UK farms.
Testing of eggs on farms is underway across the UK and results to date for England and Wales show no exposure to Fipronil.