Two Tunisian soldiers have been killed and at least another two wounded in a roadside explosion near the border with Algeria, the army has said.
The incident is the latest in a series of attacks on soldiers pursuing militant Islamists along the border.
"Two soldiers were killed... in the hunt for terrorists," army spokesman Mokhtar Ben Nasr said.
North African states have been battling to contain militants since secular regimes were ousted in recent years.
The militants - many of them linked to al-Qaeda in the Islamic Maghreb (AQIM) - easily cross the region's porous borders.
In January, 48 foreign workers were killed following a siege at the In Amenas plant in Algeria.
The raid was in response to French-led forces intervening to drive out militant Islamists from the main cities in northern Mali, which borders Algeria.
Since the end of April, around 20 security force members in Tunisia have been wounded by mine explosions blamed on the militants, AFP news agency reports.
In the latest attack, a device exploded as an army vehicle was travelling in the remote Doghra area of Mount Chaambi, Mr Ben Nasr said.
Mount Chaambi is in rugged terrain close to the Algerian border.
A security source in Kasserine, the regional capital, told AFP that one of the wounded soldiers could lose his leg.
Tunisia has had an Islamist-led government since the overthrow of long-serving ruler Zine al-Abidine Ben Ali in January 2011.
It has repeatedly accused militant Islamists of threatening Tunisia's stability.