"Terrorists" in Tunisia have abducted and decapitated an off-duty policeman, media reports on Monday cited the interior ministry as saying.
The officer and his brother were in a car in the Kef area of the northwest when gunmen seeking to rob them immobilised the vehicle.
During the robbery, the attackers discovered that the man was in the police and they kidnapped and later killed him, radio stations Mosaique and Express-FM quoted a ministry spokesman as saying.
The man's brother was not harmed in Sunday's attack.
Security forces are now engaged in a mopping up operation in the mountainous area, which is close to the frontier with Algeria.
Farther south but still in the border area a soldier on another operation was killed when a mine exploded on Monday, the defence ministry spokesman told AFP.
"Today men in a terrorist group were tracked to Mount Sammama near Kasserine," Belhassan Oueslati said.
"Aircraft were used and commando forces made a ground assault. A soldier on board a Hummer was killed when a mine exploded," he said, adding that the operation was still under way.
Since the revolution of January 2011, Tunisia has seen a rise in Islamist extremism. For the past two years, the army has been hunting jihadists in the border area.
Deadly ambushes by gunmen on the police and army are common in the region, where cross-border smuggling of fuel and food is also rife.