A group representing victims of tainted baby milk wants the head of the French dairy group Lactalis to step down after he admitted in a newspaper interview that some of its products sold may have been contaminated for over a decade. Chief of the group Emmanuel Besnier told French newspaper Les Echos on Thursday that tests had shown a factory at Craon in north-western France was responsible for the outbreak of Salmonella bacteria in 2005. The bacteria had remained at the factory until it was closed last year. A private laboratory which tested the end products had failed to notice the presence of the bacteria. If Lactalis had known about its presence, the products would never have been marketed, Besnier said. However, Quentin Guiellemain, president of an association for milk victims, said Besnier must take responsibility and resign. Lactalis recalled 12 million jars of powdered baby milk in France and from around the world when babies were taken ill last year after drinking salmonella-contaminated milk from the Craon factory. French prosecutors have started a judicial probe into the salmonella contamination.