The Dutch and Belgian authorities are raiding several addresses in both countries on Thursday as part of the investigation into fipronil contamination at numerous poultry farms and their eggs. This is a joint action from the Dutch and Belgian authorities, a spokesperson for the Dutch Public Prosecutor said to the Telegraaf, though she would not say exactly where the raids are done.

The investigation is being done by Dutch food safety authority NVWA's investigative department, on behalf of the Public Prosecutor. Belgian media reports that raids were done at eight addresses, mainly disinfecting companies that use fipronil. 

In the Netherlands the criminal investigation is so far focused on ChickFriend, a pest control company in Barneveld. The company used a fipronil containing insecticide to treat stables at over 150 Dutch poultry farms for blood lice. It is believed that ChickFriend purchased the insecticide used from a company in Weelde, Belgium - just across the border from Tilburg. The Belgian authorities already raided that company, according to the newspaper.

Fipronil in itself is not an illegal product, but it can not be used anywhere near chickens. The Wold Health Organization considers it to be "moderately toxic" to humans. In large quantities fipronil can cause liver, kidney and thyroid gland damage.