Decapitated body of a young man was found in Tunisia's central Kasserine region, in a suspected terrorist attack, a justice official said.
Senior prosecutor Mohsen Dali identified the victim as 20-year-old Oqba Al Dhibi. An investigation is under way, he said.
"The decapitated body of a young man has been found... and it is probable that a terrorist group was behind the attack."
Local radio said Al Dhibi was a shepherd who was tending his flock when he came under attack.
There was no immediate claim of responsibility.
Attacks have been carried out in the same mountainous areas of central Tunisia before, about 225 kilometres south-west of the capital.
In 2015, teenager Mabrouk Soltani was beheaded by an extremist group, a killing that fuelled public anger.
Two years later, his elder brother, Khalifa Soltani, was found dead after he was reported kidnapped by a gang in the same region.
Those two killings were claimed by ISIS.
The mountainous central region of Tunisia is also a hideout for the Tunisian branch of terrorist group Al Qaeda in the Islamic Maghreb.
Tunisian Prime Minister Hichem Mechichi condemned the "terrorist operation" and insisted the struggle "must continue".
Since its 2011 uprising, Tunisia has been hit by a string of extremist attacks that have killed dozens of security personnel, civilians and foreign tourists.
While the situation has significantly improved, Tunisia has maintained a state of emergency.