French baby-milk maker Lactalis on Thursday ordered the recall of all of the production of one of its factories since February over fears of possible contamination with salmonella.

Lactalis, one of the world's top dairy producers, had already recalled around 7,000 tonnes of infant formula milk two weeks ago.

But in what it described as "a precautionary measure" on Thursday, it had now decided -- in consultation with the health authorities -- to recall "all infant formula and nutritional products manufactured and conditioned in the Craon factory" in north western France.

"Information received from the health authorities as well as the results of initial investigations carried out... led the group to issue a second recall, this time of all products manufactured since February 15, 2017 using a specific drying tower at the factory," the statement said.

The latest recall involves 720 batches of products sold in France and overseas, compared with the initial recall of 625 batches on December 10.

It concerned powders and infant cereals of the group's Picot and Milumel brands, as well as the Taranis powdered amino-acid mix, the company said.

"We now know that there has been a low-level dispersed contamination within Craon factory, due to work during the first 2017 semester," it explained.

The Craon site was shut down on December 8 "for a thorough and comprehensive audit," it added.

On Monday, the health authorities said that 23 infants had been identified as having drunk formula milk produced at Craon and who had caught salmonellosis.

Around a dozen of the infants had been hospitalised, but had subsequently been discharged and were "doing well", the authorities said.

The father of one three-month-old baby, who drank the milk, and the UFC Que Choisir consumer association, said Monday they had filed a complaint against Lactalis.

- 'Very sensitive products' -

By recalling all of the factory's production, Lactalis was applying "the principle of maximum precaution," said Jehan Moreau, director of the French National Federation of Dairy Industries or FNIL.

"Infant milks are very sensitive products and no risks should be taken. But it's a terrible decision for them, because it will constitute a huge shortfall," Moreau told AFP.

Salmonellosis is a food poisoning that ranges from mild gastroenteritis to more serious infections. It is potentially more dangerous for young children, the elderly or weak.

The health ministry asked parents "not to use, where possible", the products concerned.

In the worst case, pediatricians recommend boiling the milk for two minutes.

Lactalis has set up a 24-hour helpline for consumers.

"We wish to extend our sincerest apologies to the families affected. We are well aware of the seriousness of the situation and fully understand the anxiety and inconvenience that have been caused," it said in a statement.