The security operation was ongoing near the town of Hydra in the Kasserine region, he said. Prime Minister Youssef Chahed, who is among 26 candidates running for president, told reporters that the extremists "were planning large-scale terrorist operations," without elaborating.
Radio Mosaique reported that two of the extremists were Algerians from the Okba Ibn Nafaa brigade, which is linked to al-Qaida's North Africa arm. Tunisian security forces have stepped up land and air operations against extremists hiding in the hard-to-reach mountainous region, where dozens have been killed in clashes in recent years.
Monday's clash came on the day Tunisia's presidential campaign officially opened, though didn't appear to be linked to the country's political situation. Since the 2011 Arab Spring uprisings against autocratic rule, Tunisia's democratic leaders have struggled to contain Islamic extremism, notably along its borders with Algeria and Libya.