Tunisia has arrested 12 people, one of them a woman, who were trying to cross into lawless Libya to join a "terrorist group", the interior ministry said.
After attacks on tourists by Islamist militants, Tunisia is especially concerned about those entering from Libya. Chaos created by two rival Libyan governments battling for control has enabled Islamic State to establish a toehold there.
Security forces arrested the 12 at a bus stop in the southern town of Ben Guerdane near the border with Libya, the ministry said in a statement late on Friday.
"The suspects said that they had been planning to cross into Libyan territory with the help of a smuggler," it said.
Tunisia made a largely peaceful transition to democracy after a 2011 popular uprising toppled president Zine al-Abidine Ben Ali. But its army has been fighting a rise in Islamist militancy.
Last month, a gunman killed 38 mostly British tourists in the Tunisian seaside city of Sousse. In March, two gunmen killed 21 foreign tourists and a policeman at Tunis's Bardo Museum. Both attacks were claimed by the Islamic State jihadist group.
Tunisia says it has started building a wall and trench along the insecure 168 km (105 miles) of its frontier with Libya. The Sousse gunman obtained training with militants in Libya before carrying out his attack.
Last month, Tunisia's parliament approved legislation allowing the death penalty for those convicted on terrorism charges and giving judges and the security forces more power to detain suspects.