Chile’s President Sebastián Piñera has suspended a rise in metro fares after two days of violent protests that brought the capital to a standstill.
Soldiers in armoured personnel carriers confronted protesters in Santiago, which is under a state of emergency.
Elsewhere, residents demonstrated by banging pots and honking car horns.
The protests have broadened to reflect general discontent about the high cost of living in one of Latin America’s most stable countries.
The unrest, the worst in decades, has exposed divisions in the nation, one of the region’s wealthiest but also one of its most unequal, and intensified calls for economic reforms.
In parts of Santiago, hundreds of troops were deployed in the streets for the first time since 1990, when Chile returned to democracy after the dictatorship of Augusto Pinochet.
A day after violent scenes, protesters erected barricades and set buses on fire, and police used tear gas and water cannon. Clashes erupted in the city centre with Mayor Felipe Alessandri describing the situation as chaotic.
Cultural and sporting events have been cancelled and the underground system has been shut down until Monday, with 41 of 136 stations vandalised.
More than 300 people have been arrested, and 156 police injured, as were 11 civilians, police said.
The military is due to help police patrol the streets during a declared 15-day state of emergency that allows authorities to restrict people’s freedom of movement and their right to assembly.
Protests were also reported in the cities of Concepción, Rancagua, Punta Arenas, Valparaíso, Iquique, Antofagasta, Quillota and Talca, according to El Mercurio newspaper.
Meanwhile, a picture of President Piñera in an upmarket Italian restaurant on Friday evening as police and demonstrators clashed in Santiago was heavily criticised on social media.
Critics said the image, reportedly during a birthday celebration for the president’s grandson, were emblematic of a leader out of touch with ordinary Chileans.