Tunisian forces launched a land and air operation against Islamist militants near the Algerian border on Friday, the military said, as Tunis battles a crisis sparked by a political slaying.
"A huge operation, with ground and air units, was launched at dawn to clean up the (Chaambi) mountain" area, armed forces spokesman Taoufik Rahmouni told Tunisian media.
The army has been tracking Islamists suspected of ties with Al-Qaeda in Mount Chaambi since December.
Rahmouni said the military launched the assault after clashes on Thursday night between soldiers and "a terrorist group," referring to fugitive Islamist militants.
"The operations will continue until they are eradicated," he later told AFP, without specifying how many militants the army was hunting.
A military source on the ground said the militants were "surrounded" in the area where eight Tunisian soldiers were slain this week.
He said helicopters had carried out air strikes.
"Either they give themselves up or they will be killed," he said.
The prime minister's office said a news conference will be held at 1430 GMT on Saturday.
The attack took place around 16 kilometres (10 miles) from the town of Kasserine, near Mount Chaambi, where the soldiers were found on Monday with their throats cut after an ambush by militants.
Mosaique FM radio said the raids were aimed at destroying militant hideouts. The explosions could be heard in Kasserine, and an AFP correspondent said they had sparked fires on the mountainside.
Tunisian troops have intensified their hunt for gunmen in Mount Chaambi since the spring, after several members of the security forces were killed or wounded by explosive devices.
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A military source also said Friday that a group of Salafists, who advocate an ultra-conservative brand of Sunni Islam, were arrested in a Kasserine mosque.
This week's gruesome killing of the eight soldiers has prompted the army in neighbouring Algeria to reinforce its presence along the border.
With the authorities admitting an increase in Islamist extremism, the Tunisian interior ministry on Friday said an "extremist" was killed and his wife wounded when an explosive device he was handling went off at his home near Tunis.
On Thursday another "extremist" lost his hand in an accidential explosion and was arrested, the ministry said earlier.
The latest violence came as Tunisian leaders opened talks with opposition and civil society representatives in Tunis to try to defuse the political crisis sparked by the July 25 murder of opposition MP Mohamed Brahmi.
The killing has been blamed on Islamists, with a connection made to the February murder of Chokri Belaid, another opposition politician -- the same gun was used in both killings.
Suspects in the Brahmi case have been named but so far no arrests have been announced.
As the political crisis enters its second week, thousands of supporters and opponents of the government have been holding rival street protests every night after breaking the Ramadan fast.
President Moncef Marzouki, a secular ally of the ruling moderate Islamic group Ennahda, has been meeting with leaders of parties demanding the government's resignation in the wake of the killings.
Prime Minister Ali Larayedh of Ennahda held separate talks with General Union of Tunisian Labour (UGTT) head, Houcine Abassi, whose organisation called a general strike earlier this week and wants the formation of a government of technocrats.
Larayedh proposes enlarging the coalition, ruling out a resignation of the Ennahda-led cabinet, which detractors charge has failed to rein in radical Islamists accused of a wave of attacks since the 2011 revolt that ousted president Zine El Abidine Ben Ali.
He has called a general election for December 17.
The authorities have pointed to links between the Chaambi militants, the assassins of Brahmi and Belaid and Tunisia's main Salafist organisation Ansar al-Sharia, which denies the accusations.