At least 14 Tunisian soldiers have been killed in a militant attack near the Algerian border with at least 20 others wounded, the defence ministry says.
They say gunmen, armed with rocket-propelled grenades and rifles, raided two checkpoints near Mount Chaambi.
It is reportedly the heaviest death toll registered by the army since independence in 1956.
The Tunisian army has been waging a crackdown on militants operating in the mountainous region over the past year.
Islamist militants, including fighters linked to al-Qaeda in the Islamic Mahgreb (AQIM), are believed to be hiding out in the border region.
Tunisians are in shock after what is being described as the deadliest attack on its armed forces since independence. The public is calling into question the strategy of the government, with renewed criticism being directed at Interior Minister Lotfi Ben Jeddou.
Following the attack, Prime Minister Mehdi Jomaa set up a “crisis cell” to come up with a coordinated government strategy. Details of exactly which militant group carried out the attack remain opaque – more information is expected later in the day.
The soldiers were attacked “by terrorist groups” on Wednesday evening as they were breaking their fast as part of the Muslim holy month of Ramadan, Tunisia’s Tap state news agency reports.