Rached Ghannouchi, the head of Tunisia's ruling Islamist party, said he backs the application of the death penalty, describing it as a "natural law" in a television interview to be broadcast Monday evening.
"We say that capital punishment is a natural law, a soul for a soul. And whoever threatens the life of another must know that his life is also threatened," the Ennahda party's veteran chief told news channel France 24.
He was asked in particular about the punishment of rapists, after a number of incidents in Tunisia, including the case of a three-year-old girl repeatedly raped by the caretaker of a children's nursery, which has caused shock and anger.
"This crime must be sanctioned in the severest possible way and I would even say yes, by capital punishment," Ghannouchi said.
"Rape is like a death sentence for a woman and for the entire family."
Under Tunisia's penal code, rape, murder, acts of terrorism and plotting against the state are punishable by death, but in practice no executions have been carried out in Tunisia since 1991.
Amna Guellali, the Tunisian representative of Human Rights Watch, said she regretted Ghannouchi's comments, which follow efforts by rights groups to get the death penalty's abolition inscribed in the new constitution currently being drafted.
"It is a setback, given that Tunisia has a moratorium on the death penalty. It's a challenge to that and it's quite serious," she told AFP.
Guellali said the Islamist leader was publicly expressing the position of a number of members of his party, who believe the death penalty is "something natural, an obligation in Islam and a just penalty for... an atrocity that has been committed."
Ennahda, which heads Tunisia's coalition government, is frequently accused by the secular opposition and rights activists of seeking to Islamise society and impose the key provisions of sharia, or Islamic law.