Myriam Jaouen, 30, was charged with murder but the court in the southeastern city of Lyon found her guilty of "torture" and "barbarism resulting in death," but with no intention to kill.

There is an "unfathomable" element to the 2022 killing of baby Lisa, said prosecutor Baptiste Godreau, adding that Jaouen was "perfectly conscious" of what she was doing.

He said that the "heavy" sentence was needed to punish "the extreme seriousness of this act, for having taken the life of a defenceless child in a cowardly fashion, to protect society in a lasting way and to protect the interests of the family".

The accused admitted in police custody that she had given Lisa the corrosive liquid, but insisted that she had not intended to kill her.

She gave several versions before admitting during the trial that she had held the child's head and poured the product directly into her mouth.

She said that she could no longer bear the infant's crying.

Baby Lisa's parents were "shocked" that Jaouen had not been convicted of murder, their lawyer said after the trial.

The verdict "adds pain to pain," Catherine Bourgade told reporters, adding that the parents "have the impression of having lost their child twice."

"Who can put drain cleaner into the mouth of a child and then tell us that she didn't mean to kill her?" Bourgade said, adding that she hoped the prosecution would appeal the verdict.

- 'Cowardice' -

Godreau denounced the defendant's "cowardice" after the incident, saying she did not call for help herself, got rid of the bottle before she finished her workday and then went shopping, seemingly indifferent to the baby's "agony."

Jaouen attended the proceedings with her back often hunched, without showing much emotion.

At the time of the killing, the woman, who is partially deaf, was living with her parents after a difficult school career and on-off jobs in the sector.

Despite her lack of experience, Jaouen was hired by the People and Baby group, a major player in the creche sector in France, which managed the nursery.

On June 22, 2022, she was alone at the opening of the facility when Lisa's father dropped off the infant.

A few minutes later, two women who had come to drop off their sons found the employee panicking and the child vomiting.

The girl, seriously burned, died hours later at the hospital where she was taken.

The death sparked outrage in France and triggered investigations by the government and media which highlighted shortcomings in the private daycare sector.

In their evidence at the trial, Lisa's parents sought to highlight the responsibility of the defendant, whom they described as the "monster" who killed their daughter.