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.

He said the chase was still underway, without giving further details.

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.

The last major attacks were a series of deadly operations in 2015 and an IS offensive into the town of Ben Guerdane in March 2016.

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