A roadside bomb targeting a Tunisian army vehicle killed two soldiers on Thursday in the mountainous border region near Algeria where security forces have been hunting Al-Qaeda linked jihadists, the military said.
"At around 7:45 am (0645 GMT), two soldiers were killed and two others wounded when a device exploded as their vehicle passed by in the Doghra area of Mount Chaambi," said spokesman Mokhtar Ben Nasr.
A security source in Kasserine, the regional capital, told AFP that one of the two wounded soldiers could lose his leg.
Mount Chaambi is a rugged frontier region where the Tunisian army has been tracking militants the government says are veterans of the Islamist rebellion in northern Mali with links to Al-Qaeda in the Islamic Maghreb (AQIM).
The authorities in Tunisia have been hunting the extremist group since December when it attacked a border post, killing a member of the national guard.
The army has intensified its search since the end of April, using mortar fire and dogs, after home-made landmines planted by the jihadists to protect their base wounded a dozen soldiers.
In all around 20 soldiers have been injured by bombs but the latest attack marks the first time troops have been killed.
On Saturday, three soldiers were wounded in the Mount Chaambi area when a landmine exploded underneath their vehicle, and another was accidentally shot dead by colleagues during an operation there on Sunday.
The authorities say none of the militants - a group of about 30 comprising Algerians, Libyans and members of Tunisia's radical Salafist group Ansar al-Sharia -- has so far been killed in the western region.
Interior ministry spokesman Mohamed Ali Aroui said on Friday that since December 45 "terrorists" linked to the group have been arrested.
He said the cell was called the Okba Ibn Nafaa brigade, after a 7th century Arab leader who brought Islam to Tunisia, and was preparing attacks against the Tunisian security forces.
The army said last month that it had dismantled their base in Mount Chaambi, where they found tents, explosives, maps and mobile phones used by the group.
Since the revolution that ousted Zine El Abidine Ben Ali, Tunisia has been rocked by waves of violence blamed on hardline Islamists who were suppressed under the former dictator.
Ansar al-Sharia is the most radical of the extremists groups to have emerged, and the government accuses its fugitive leader, a former Al-Qaeda fighter in Afghanistan known as Abu Iyad, of orchestrating an attack on the US embassy last September.
The Salafist movement has in the past denied any link to the militants being hunted in the remote border region.
The ongoing military operations in Mount Chaambi are considered the most serious in Tunisia since clashes in 2007 between the army and a group of around 30 Islamists in Soliman, near the capital, in which a soldier, two policeman and 11 Islamists died.