Dutch prosecutors said in a statement on Thursday that the men are directors of a company that allegedly used an unauthorized insecticide at poultry farms.

Investigators in the Netherlands and Belgium made the arrests during a string of coordinated raids linked to their probe into how fipronil, which can be harmful to humans, made it into the food chain.

"The Dutch investigation focused on the Dutch company that allegedly used fipronil, a Belgian supplier as well as a Dutch company that colluded with the Belgian supplier," the prosecutors said.

"They are suspected of putting public health in danger by supplying and using fipronil in pens containing egg-laying chickens."

Authorities in the Netherlands, Belgium and Germany recalled millions of eggs at the start of the month after the discovery of fipronil in batches delivered to supermarkets. Dozens of poultry farms, mainly in the Netherlands but also in Belgium, have been closed down, while supermarkets have cleared tainted eggs from their shelves.

The French agriculture ministry confirmed on Friday that 250,000 contaminated eggs had been "on the market" in France between April and July. Five companies using egg products were been involved. A first batch of 196,000 eggs from Belgium had been placed on the market between April 16 and May 2 and a second lot from the Netherlands of 48,000 eggs had been sold through Leader Price shops between July 19 and 28. 

The insecticide is a common ingredient in anti-lice treatments, but it is banned from being used on animals destined for human consumption. Fipronil can be hazardous to humans' kidneys, liver and thyroid glands, according to the World Health Organization, but only if consumed in large quantities.

Scandal spreads

The European Commission said on Friday a total of 15 countries have been affected by the fipronil-contaminated eggs, including two non-EU countries, Switzerland and Hong Kong.

The two countries received eggs originating from affected poultry farms in Belgium, the Netherlands, Germany and France, it said.

The Commission is planning a crisis meeting of EU ministers on September 26.

One ton of contaminated egg yolk liquid was uncovered in Romania later on Thursday, according to the country's veterinary health authority ANSVSA. It was the first discovery of contaminated egg product in eastern Europe since the scandal erupted.

The egg yolk liquid was found in a warehouse on the western side of the country and had been imported from Germany, but "none of the product has been offered for sale," said ANSVSA.

British authorities reported earlier on Thursday that around 700,000 eggs from affected Dutch farms had been distributed in Britain. The UK Food Standards Agency (FSA) said the eggs were mixed in large batches to be used in processed foods and not sold fresh, as they were in countries like the Netherlands and Germany. Four major British grocery chains have withdrawn such products, including sandwiches and salads, the FSA said in a statement.

"However, as this represents 0.007 per cent of the eggs we consume in the UK every year, it remains the case that it is very unlikely that there is any risk to public health from consuming these foods," the statement said. The FSA also said that the recalls were not being carried out owing to safety concerns, but because the ingredient is not authorized for use.

Luxembourg said that eggs sold in the discount supermarket Aldi had been withdrawn after one batch was found to contain sufficient levels of fipronil to potentially pose a threat to young children, who cannot consume as much as adults safely. Aldi earlier this month pulled all Dutch eggs from its stores in Germany,but the company said on Thursday that its German markets would restock eggs as of Friday.

rs,jm (AFP, AP, Reuters, dpa)