Interior ministry spokesman Khalifa Chibani told AFP the National Guard had received information concerning "two male suspects" in the region bordering Libya.

They tracked them in the Magroun region near a nature reserve and tried to arrest them but "one of them blew himself up," he said.

"The other suspect was armed with a Kalashnikov" assault rifle and opened fire on the police but there were no injuries, he said.

After an exchange of fire, security forces "shot dead the second terrorist", the interior ministry said later, adding that the National Guard and the army were searching the area.

The identity of the two suspects was not immediately clear.

Since its 2011 revolution, Tunisia has faced a jihadist insurgency responsible for the deaths of dozens of soldiers, police, civilians and foreign tourists.

Tunisia has been under a state of emergency since November 2015, when a suicide bombing in Tunis claimed by the Islamic State jihadist group killed 12 presidential guards.

Monday's unrest comes after a series of deadly operations in 2015 and two years after an IS offensive into the town of Ben Guerdane.

On March 7, 2016, jihadists launched brazen attacks on the town that killed 13 members of the security forces and seven civilians and also left 55 fighters dead.

Prime Minister Youssef Chahed this month marked the anniversary of the Ben Guerdane attacks and said he wanted to "consecrate March 7 as a national day of victory against terrorism" and Ben Guerdane as "the town of victory against terrorism".

Thousands of Tunisians have joined jihadist groups fighting in Iraq, Syria and neighbouring Libya.