An urgent investigation has been launched to discover where thousands of imported eggs now implicated in a European contamination scare were on sale across the UK.
The Food Standards Agency said around 21,000 eggs produced on Dutch farms and feared tainted by the pesticide Fipronil went onto British supermarket and shop shelves between March and June.
It is thought disinfectant used in products on chicken farms is to blame for a scare that has seen millions of eggs taken off shelves in Germany and the Netherlands and also implicated Belgian farms.
The FSA said the UK health threat remains "very low" as the affected batches are no longer on sale and the "low level of potential exposure" means consumers should not be concerned.
Reported adverse effects from eating the contaminated eggs include sweating, nausea, vomiting, head and stomach pain, dizziness and seizures.
The British Egg Industry Council said there was no need for people to "change the way they cook or consume eggs".
The body said buyers should look for the British Lion mark to ensure they are getting "safe British eggs", which are around 85% of the eggs eaten annually in the UK.
The number of eggs involved in the scare represents about 0.0001% of the almost two billion eggs imported into the UK each year.