Dahbia Benkired was handed an "irreducible life sentence" for killing 12-year-old Lola Daviet in the French capital in 2022, in a case that horrified the country and sparked anti-immigration fervour because the woman did not have the right to be in France.

The sentence is the harshest under the French penal code.

"We believed in justice and we got it," said Lola's mother, Delphine Daviet following the verdict.

Benkired, now aged 27, was detained after Lola Daviet went missing in the northeast of Paris.

Her body was then found in a trunk in the lobby of the building where her father and mother worked as caretakers.

In the verdict, the presiding judge cited the "extreme cruelty of the criminal acts", describing them as "true torture" and "total dehumanisation".

"In determining the appropriate sentence, the court took into account the unspeakable psychological damage to the victim and her family in such violent and almost unspeakable circumstances," he said.

The public prosecutor had argued earlier in the day that Benkired should be handed an "irreducible life sentence", saying it reflected the "extreme gravity" of the crimes and "the suffering" they caused her family.

Lola's brother Thibault Daviet thanked the justice system after the ruling.

"We have restored the memory of my sister, we have restored the truth," he said.

Since its introduction in 1994, only four men have received the same maximum sentence.

Those given it may in theory, after 30 years, ask a judge to review the ban on seeking parole.

- 'Psychopathic' -

Building residents saw Benkired in the lobby of the apartment block in the 19th district on October 14, 2022, carrying suitcases and a heavy trunk covered in a blanket, the investigation showed.

An hour and a half earlier, security footage showed Benkired approaching the girl as she returned from school, then leading her into the flat her sister occupied in the building.

Benkired raped and hit the schoolgirl with scissors and a box cutter, then bound her up in duct tape, including around her face, leading to her death by asphyxia.

Benkired apologised for her "horrible" actions when her trial opened last week.

But three psychiatric experts said they had noted "psychopathic" tendencies in the defendant, and did not think she suffered from any mental health condition that could be cured.

She was found competent to stand trial.

-'Systematic expulsion'-

Conservative and far-right politicians seized on the case to call for better immigration law enforcement, after Benkired was found to have overstayed a student visa and failed to comply with a notice to leave France.

During the trial, Benkired described growing up in a dysfunctional family, a childhood spent between Algeria and France, unloving aunts and a violent father.

She settled in France in 2013 but had no stable job or residence.

Following the verdict, far-right leader Marine Le Pen welcomed the decision to hand Benkired the toughest possible sentence, renewing calls for the "systematic expulsion" of foreigners who commit crimes.

The victim's mother has urged politicians to stop exploiting her daughter's death.