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. 
Protests return to Tunisia as trading route is closed
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. He who wants to go on strike can do it, but without disrupting work," Essebsi added.
However, the coordinator of a sit-in in El-Kamour, near oil fields in southern Tunisia, remained defiant in the wake of Essebsi's speech.
"We will not give in," Tarek Haddad said on Mosaique FM radio station.
The unusual step of military deployment raised concerns in Tunisia about freedom of expression.
"This is not the army's job" Mohammed al-Hameidi, an official in the opposition Democratic Alliance Party, told the DPA news agency.
"The presidential order also poses the threat of militarising the political sphere," Hameidi added without elaborating.
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.
Unemployment in Tunisia stands at around 15 per cent, according to official figures. Protesters have often staged strikes and sit-ins that block access to production sites, costing the state billions of dollars.