Tunisia's army launched a "huge" operation to track down jihadists in the central Sidi Bouzid region Tuesday, the defence ministry said, after militants killed six policemen in the area last week.

"A huge military operation was launched on Tuesday in the hills of Sidi Ali Ben Aoun," a district of the Sidi Bouzid region, ministry spokesman Taoufik Rahmouni said, quoted by the official TAP news agency.

The army has deployed tanks and helicopters to support the operation aimed at hunting down "terrorists," he added.

Sidi Ali Ben Aoun is seen as a bastion of support for Salafism, an ultraconservative brand of Sunni Islam. Khatib Idrissi, a key figure in Salafist circles, lives in the area.

Militants killed six policemen in the area last Wednesday, and security forces have arrested eight men they say took part in the attack, according to the interior ministry.

National guard units also killed an Algerian jihadists and seized explosives and weapons when they captured the eight men, the interior ministry has said.

Since the uprising that ousted Zine El Abidine Ben Ali's regime in 2011, the country has been hit by rising violence blamed on jihadist groups suppressed under the veteran strongman.

In October alone, nine members of the security forces have been killed in clashes with what the government calls "terrorist" groups.