Troops’ deployment comes after protests erupt at industrial sites amid growing discontent over bad economic conditions.
Tunisia’s President Beji Caid Essebsi has ordered the army to protect the output of the country’s main resources following a wave of protests over unemployment and worsening economic conditions.
It is the first time that troops in Tunisia were deployed to guard industrial installations, including phosphate, gas and oil production facilities, that are key to the national economy.
"It is a serious decision, but it must be applied to protect our resources," Essebsi said on Wednesday in a speech to the nation.
"Our democratic path has become threatened and law must be applied but we will respect freedoms."
Since the 2011 revolution, Tunisia’s democracy has advanced with free elections and a new constitution. Yet, the government has faced growing social discontent over the economy, especially in inland regions.
Protesters have often staged strikes and sit-ins that block access to production sites, costing the state billions of dollars.
Tunisia is trying to enact sensitive reforms to help growth, but many unemployed youth in the marginalised south still feel they have gained few opportunities.
For several weeks, about 1,000 protesters in Tatouine province, where Italy’s ENI and Austria’s OMV have gas operations, have been demanding jobs and a share in revenue for the area’s natural resources.
Protests have also broken out in another southern province, Kebili.
Demonstrations that hit the phosphate sector in past years cost the country more than $2bn, according to officials. But production there has returned to the highest levels since 2010 after officials negotiated deals with protesters.
Tourism, another key earner for the government accounting for about eight percent of the economy, was badly hit by two attacks on foreigners in 2015.
Bookings, however, are returning and officials expected 30 percent tourism growth this year.