Chilean authorities extended a curfew for a second consecutive night on Sunday after two people died in a torched supermarket amid a wave of unrest over price hikes and social inequality.

Police and the military fired tear gas and used water cannon against protesters in the capital Santiago as clashes raged through a third day.

President Sebastian Pinera – who introduced a state of emergency on Friday and deployed thousands of troops onto the streets – defended the measures.

“Democracy not only has the right, it has the obligation to defend itself using all the instruments that democracy itself provides, and the rule of law to combat those who want to destroy it,” Pinera said after an emergency meeting with top state officials.

The conservative president met late on Sunday with the chairmen of the Congress and Senate and the head of the Supreme Court.

Interior and Security Minister Andres Chadwick said two women burned to death after a store owned by US retail chain Walmart was set alight in the early hours of Sunday.

A third victim, who authorities initially had said had died in hospital, suffered burns on 75 per cent of her body.

Chadwick said two people suffered gunshot wounds following a clash with police who responded to a report of looting in a town south of Santiago.

Authorities reported 103 serious incidents throughout the country with 1,462 people detained, 614 in Santiago and 848 in the rest of the country. (AFP)