The death of a student demonstrator last Thursday further inflamed tensions [EPA]
Chile has dismissed five policemen, including a general, over the death of a teenager during a mass protest last week.
The death of 16-year-old Manuel Gutierrez further inflamed tensions in Chile, where students, unions and supporters have been protesting for months.
The government had initially denied that police had fired on the demonstrators, but the commander of the Santiago metropolitan police admitted earlier on Monday that a patrol officer "made the decision to use his service weapon, an Uzi nine millimeter, on two occasions".
General Jose Luis Ortega said the police officer, one of the five to be sacked "said he fired, not at a group of persons, but in the air" after police saw protesters firing at them.
"We are not assigning responsibility (for Gutierrez's death) to the officer who used his service weapon. That will have to be established scientifically by the technical studies that will be carried out," Ortega said.
President Sebastian Pinera, who has seen his popularity plunge during the protests, on Sunday promised to get to the bottom of the death.
Gutierrez was shot to death last Thursday during clashes between police and protesters in Macul, an area east of Santiago, one of hundreds of places around the country where unrest broke out during the 48-hour general strike last week.
Before dawn on Monday, demonstrators blocked access to Chile's largest copper mines by setting barricades on fire as unions declared a general strike in Calama, a town 980 miles from the capital.
Demonstrators shut down access to the mines, demanding the government puts aside a percentage of mine revenues to go to infrastructure in the region.
Later in the day, thousands of protesters marched through the town in support of the coal miner and student movements.
Mining is Chile's lifeblood, providing 40 percent of state earnings, and the country's National Union of Workers of Industrial Assembly and Civil Works, which represents 50,000 miners, donated $21,000 (10m Chilean pesos) to the Chilean Confederation of Students over the weekend.
"We have said that this protest will not stop until the government gives us the answer that we are waiting for," said Esteban Velasquez, the mayor of Calama.
Police in riot gear used tear gas and water cannons against protesters and arrested 14 protesters, including Velasquez.
More than 1,200 demonstrators have been arrested throughout the unrest of the past three months.
Among the students' demands are a state takeover of the public school system, which is currently run by local authorities. Protesters claim this system has created deep inequalities in educational access.
Students also want easier access to higher education, saying that the current system leaves university graduates in deep financial debt.
Tuition fees for higher education in Chile are the highest in the world when adjusted for the country's per capita gross domestic product.
Chile has the highest per capita income of any country in South America, but the continent's widest income gap between rich and poor.
Chile's president has called for a "constructive dialogue aimed at finding solutions", and announced he was rescinding a seven per cent health insurance tax on the pensions of poor senior citizens.
The Chilean Confederation of Students accepted an invitation to meet with the president on Tuesday.