Tunisia, the birthplace of the Arab Spring, has suffered from a wave of jihadist violence since its 2011 revolution that ousted longtime dictator Zine El Abidine Ben Ali.
In today's deadliest violence, four policemen were killed when a militant detonated his explosives belt after a firefight erupted in the Tatouine governorate, said the interior ministry.
A national guard unit had carried out the raid acting on information from an "anti-terrorist" operation earlier the same day near Tunis.
In the earlier raid, two suspected jihadists were killed during a raid near the capital against a cell planning "simultaneous" attacks, the same source said.
Sixteen others were arrested during the operation in Ariana province just outside Tunis, and Kalashnikov assault rifles, pistols and ammunition seized.
The interior ministry said the suspects had gathered in the area from different parts of the country.
A resident of the Sanhaji district told AFP that a two-hour gunbattle erupted with the suspects after the national guard launched the raid at around 8:00 am (0700 GMT).
The Islamic State group claimed brazen attacks last year on the National Bardo Museum in Tunis and a beach resort near Sousse that killed a total of 60 people, all but one of them foreign tourists.
A November suicide bombing in the capital, also claimed by IS, killed 12 presidential guards and prompted the authorities to declare a state of emergency.
