The children, the youngest of whom is 20 months old, had eaten defrosted hamburgers made by the French company SEB which said the meat was taken from animals slaughtered in Germany and processed in France.
"They are in a serious but not worrying state. Their lives are not at all in danger," a spokesman for the Regional Health Agency (ARS) in Lille, northern France, where the children were hospitalised on Wednesday, told AFP.
The "Steak Country" burgers were bought in French branches of German supermarket Lidl. SEB said it had recalled them and Lidl said it had removed them from its shelves in France.