Assailants killed 14 Tunisian soldiers in an attack near the Algerian border, the government said Thursday, the worst such attack in the army's history as it presses a crackdown on Al-Qaeda-linked jihadists.
The attack took place on Wednesday evening as Tunisians were breaking their day-long Ramadan fast, with two "terrorist groups" opening fire on twin army posts with machine guns and grenade launchers, the defence ministry said.
It gave no details of the groups.
But the ministry has previously insisted that militants the army has been hunting since late 2012 in the remote Mount Chaambi border region, where the soldiers were killed on Wednesday, are linked to Al-Qaeda in the Islamic Maghreb (AQIM).
"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.
"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.
President Moncef Marzouki declared three days of national mourning on Thursday.
Government spokesman Nidhal Ouerfelli condemned what he called a "heinous act" and underscored the unwavering determination of the authorities to defend Tunisia.
"Our national army is determined to continuing its fight against terrorism whatever the sacrifices, for the benefit of our nation," defence ministry spokesman Lamjed Hammami told reporters late on Wednesday.
The attacks came almost a year to the day after eight Tunisian soldiers were found with their throats slit after being ambushed in the western Kasserine region.
- Political gains, jihadist threat -
Since the 2011 revolution that toppled Zine El Abidine Ben Ali and touched off the Arab Spring, Tunisia has been rocked by violence blamed on hardline Islamists who were suppressed under the former dictator.
The country has made tangible progress this year in terms of stability, and elections are due to take place in just over three months, after the assassination of two opposition politicians in 2013 triggered political turmoil.
In January, after a tense standoff between the rival factions, parliament finally adopted a new constitution and the ruling coalition led by moderate Islamist party Ennahda resigned, allowing for the formation of an interim administration of independents.
But the jihadist threat has cast a shadow over any political gains.
Four Tunisian soldiers were killed by a land mine in the northwest Kef region during an anti-terror operation earlier this month, a day after four soldiers and two policemen were wounded by a roadside bomb in the same area.
Last month AQIM, the global terror network's North Africa branch, for the first time claimed responsibility for recent attacks in Tunisia, including an assault in May on the home of the interior minister.
The May 27 attack on the home of Lotfi Ben Jeddou, in the Kasserine region, killed four security guards.
Officials insist it was a "revenge" attack in response to successes achieved by the security forces in their anti-terrorist campaign.
But the previous month the authorities designated Mount Chaambi and neighbouring mountain districts a closed military zone, and warned of the growing threat posed by "terrorist organisations" based there.
Since December 2012, Tunisia's security forces have been battling the jihadists hiding out in the Mount Chaambi and Kef regions, which both straddle the Algerian border, launching a series of major land and air operations.
Authorities say they have gained the upper hand, while acknowledging the campaign to root out all the jihadists will take time.