At least 14 Tunisian soldiers were killed and 25 injured in attacks by militant Islamists at two military checkpoints in the Chaambi mountains near the border with Algeria, the state news agency TAP reported Thursday.
Maj. Col. Souheil Chmengui, who heads the Tunisian army's operations, told the news service that five soldiers died of gunshot wounds and nine were burned to death when their tent was attacked. Medical personnel said three of the injured were in critical condition.
The attack, described by the Defense Ministry as the deadliest against the army since the country's war for independence in 1956, is the second to target the army this month, after a land mine killed four soldiers in the mountain area on July 2.
A special unit has been formed by the government to investigate the latest attacks as interim President Moncef Marzouqi announced a three-day period of national mourning.
Tunisia has struggled with insurgents in the Chaambi mountains over the last year since militants killed eight soldiers on July 29, 2013, an incident that eventually led to the resignation of the Cabinet.
In April, Marzouqi declared a "closed operations area" in the mountains, where he deployed thousands of soldiers in an attempt to crack down on armed Islamists spearheaded by Al Qaeda in the Islamic Maghreb.
Gen. Mohamed Saleh Hamdi, the army's chief of staff, said at a news conference that Tunisians should be prepared for a long and exhausting fight against terrorism.
"We have to be psychologically prepared for further losses. Tunisia's war against terrorism is a war of nerves and we are determined to win it," he said. "I hope no similar attacks will take place, but deep inside me I'm sure we will witness other attacks."