The French dairy group at the centre of a baby milk scandal, Lactalis, has admitted some of its products may have been tainted over more than a decade.
Millions of boxes of powdered milk have been recalled worldwide following a salmonella outbreak last year.
Researchers say that the exact same strain of salmonella was responsible for another outbreak in 2005.
The company said it was possible other babies could have been affected by Lactalis products since then.
In a newspaper interview published on Thursday, Lactalis CEO Emmanuel Besnier said tests had shown that a factory at the centre of the latest scare, in Craon in north-western France, was also responsible for the 2005 outbreak.
The factory – owned by Lactalis since 2006 – was closed in December after it emerged that contamination had started in one of its drying towers.
How many babies have been affected since 2005?
In the 2005 outbreak, 146 children fell ill. In last year’s outbreak, at least 38 cases in France and Spain were traced to Lactalis milk.
On Thursday, researchers from the Pasteur Institute in Paris said the salmonella bacteria had remained at the Craon factory until it was closed.
As a result, they said, a total of 25 babies had been affected between 2005 and 2016.
Mr Besnier appeared to point to a similar conclusion in his interview with Les Échos newspaper.
“The possibility that babies consumed tainted milk over this period cannot be ruled out,” he said.
What are the consequences for Lactalis?
The crisis, Mr Besnier said, would “cost Lactalis hundreds of millions” of euros.
Lawsuits have been filed by parents who say their children became sick after drinking Lactalis products.
Moreover, the company has recalled nearly a whole year’s output from the Craon factory – about 12 million boxes of powdered milk – which had been distributed to 83 countries.
A company spokesman told the BBC last month that those countries were in continental Europe, Asia, Latin America and Africa. The UK, US and Australia were not affected.
Lactalis has annual sales of €17bn ($21bn; £15bn), production sites in 47 countries and employs 15,000 people in France alone.
What are the dangers?
Salmonella can cause diarrhoea, stomach cramps, vomiting and severe dehydration. It can be life-threatening, especially in young children.
The illness, caused by intestinal bacteria from farm animals, is dangerous for the very young and the elderly.
None of the affected children have died in this outbreak.
The government crackdown
Products from Craon have been banned while French authorities are carrying out investigations. Lactalis says it is fully co-operating.
The government has warned the company it must expect penalties over its handling of the affair.
It also threatened to impose sanctions against retailers last month, after it emerged that several major supermarket chains had continued to sell products that could have been contaminated.