France’s biggest supermarket chains said they sold some Lactalis baby food products after a recall by the dairy giant over concerns they could be contaminated with salmonella, wrote reuters.

Retailers Carrefour, Leclerc, Auchan and Systeme U independently said products including infant formula milk had remained on their shelves after the recall last December, deepening a health scare which has prompted a French inquiry after three dozen children fell ill.

Salmonella infections can be life-threatening, particularly for young children, and the recall risks damaging Lactalis in China, a fast-growing market for baby food and dairy products where consumers are highly sensitive after melamine-tainted baby milk led to the deaths of six children in 2008.

Privately-held Lactalis, which has annual sales of around 17 billion euros, has addressed the salmonella contamination by halting operations at the factory where it started. On Thursday, Lactalis announced the temporary lay off of 250 workers.

The product recall affected goods carrying the Picot, Milumel and Taranis brands destined for French and overseas markets and France’s consumer protection agency DGCCRF has begun an investigation and carried out more than 2,000 checks so far.

“We made mistakes, as did all the big distribution companies,” Systeme U spokesman Thierry Desouches told BFM TV, adding that the recall had been complex and that the company had not dragged its feet.

“We’re speaking about a volume of products that perhaps earned us a total margin of 300 euros. Would we risk our image for such a derisory amount?” Desouches said on Thursday.

French Agriculture Minister Stephane Travers told the retailers to ensure such a “huge mess” did not happen again.

The DGCCRF issued a first recall on Dec. 10 after Lactalis discovered salmonella contamination at its Craon factory, halting the sale of several baby food products made there.

Lactalis announced an extension to the recall less than two weeks later, confirming that contamination occurred at Craon during work in the first half of the year.

In a statement on Thursday, Carrefour said it had sold 434 products at risk of contamination since the Dec. 21 recall, but that another 95,000 had been successfully removed from shelves.

Leclerc, France’s biggest food retailer, said it had sold 984 products involved in the recall.

The recall included products also aimed for export, including to China, Taiwan, Pakistan, Afghanistan, Iraq, Morocco, Lebanon, Sudan, Romania, Serbia, Georgia, Greece, Haiti, Colombia and Peru, while some were destined for markets, including Africa and Asia.

Lactalis is one of the world’s largest dairy companies and has been expanding its infant nutrition business, although its biggest categories are cheese and liquid milk.