Tunisia has carried out air raids on fighters holed up in the Mount Chaambi area near the Algerian border.
Tunisian warplanes bombed the caves on Monday as part of an operation launched on August 1, after eight soldiers were found with their throats cut after being ambushed last month.
An army source said security forces had killed several fighters and captured at least four others in the same region on Sunday. One of the detained men admitted to taking part in the killing of the soldiers, local media said.
The captured man was reportedly found in the possession of video footage taken with a mobile phone showing some of the soldiers having their throats slit.
Tunisia is in the throes of its worst political turmoil since autocratic president Zine el-Abidine Ben Ali was toppled in early 2011 in the first of the so-called Arab Spring uprisings.
The government, led by the Islamist Ennahda party, has been grappling with a protest movement whose secular leaders have called for tougher action against fighters they say threaten Tunisia's fragile young democracy.
The crisis appeared to be deepening with both the Ennahda coalition and the opposition calling for rival rallies on Tuesday.
The opposition is demanding the resignation of the government and dissolution of the elected National Constituent Assembly since the July assassination of MP Mohamed Brahmi.