A group of suspected al Qaeda members opened fire on Tunisian forces killing four, a security source told Reuters.
Three of the nine armed men were killed in the clash in the northern town of Rouhia.
Arab and Western officials have warned al Qaeda could be exploiting the conflict in neighbouring Libya to acquire weapons and smuggle them into other countries.
“Nine armed people opened fire on the military and police at a checkpoint. The military returned fire,” said the source, who declined to be named.
“The armed men were Tunisian, Algerian and Libyan,” the source said, adding they were believed to be members of al Qaeda in the Islamic Magreb (AQIM).
Tunisian security forces on Sunday arrested two people suspected of being members of the North African group near the Libyan border who were carrying an explosives belt and bomb.
Al Qaeda in the Islamic Magreb is one of the group’s biggest regional branches and has also carried out kidnappings in recent years.