French police are searching several sites run by dairy group Lactalis as part of an ongoing investigation into a baby milk scare.
More than 12 million boxes of powdered baby milk have already been recalled in 83 countries following a salmonella outbreak.
Lawsuits have been filed by parents who say their children became unwell after drinking the formula.
Sites raided include a factory in Craon, north-western France.
The factory was closed last month after it was thought the contamination started in one of its drying towers.
Lactalis spokesperson Michel Nalet confirmed the police presence. “As we have said before, Lactalis is cooperating with justice authorities and will provide everything necessary for a smooth conduct of the investigation,” he told AFP news agency.
At least 37 babies have been affected in France.
The Lactalis group is one of the world’s largest producers of dairy products, with annual sales of €17bn ($21bn; £15bn), It has 246 production sites in 47 countries and employs 15,000 people in France alone.
Last week a spokesman told the BBC that all the countries affected had been informed, in Europe, Asia, Latin America and Africa. The UK, US and Australia were not affected, he added.