"The toll is 14 dead soldiers and 20 wounded, and it is expected to rise," the defence ministry said, updating an earlier toll of four killed during the attack in the Mount Chaambi area.
"This is the heaviest recorded (death toll) to have been registered by the army since independence" in 1956, the ministry's press office told AFP.
The attacks came almost a year to the day since Tunisian soldiers were ambushed in the same region of Mount Chaambi, where the army has been hunting down a group with links to Al-Qaeda.
Last month Al-Qaeda in the Islamic Mahgreb, or AQIM, for the first time claimed responsibility for recent attacks in Tunisia, including an assault in May on the home of the interior minister that left four security guards dead.
Also Read
The May 27 attack on the home of Lotfi Ben Jeddou, in the western Kasserine region, killed four policemen.
Since late 2012, Tunisia's security forces have been battling jihadists hiding out in the Mount Chaambi and Kef regions and thought to be linked to AQIM.
Authorities say they have gained the upper hand in the fight against jihadists active along the Algerian border, while acknowledging the campaign to root them all out will take time.