Santiago (AFP) - Chile announced Friday it will stage a referendum to replace the country's dictatorship-era constitution -- a key demand of protesters after nearly a month of sometimes violent civil unrest.

The current charter, in force since 1980 and enacted by the former military junta of Augusto Pinochet, has been changed numerous times in the years since.

But it does not establish the state's responsibility to provide education and healthcare -- two demands made by millions of Chileans who have taken to the streets.

Lawmakers in Chile's National Congress agreed early Friday to hold the plebiscite in April 2020 after hours of intense negotiations between the governing coalition and opposition parties.

"This agreement is a first step, but it is a historic and fundamental first step to start building our new social pact, and in this the citizenry will have a leading role," said Interior Minister Gonzalo Blumel.

The referendum will ask voters whether the constitution should be replaced and if so, how a new charter should be drafted, Senate president Jaime Quintana said.

It will propose three different models for a body to devise a new constitution, made up of either fully elected representatives, political appointees or an equal mix of both.

If elections to the body are needed, they will be held in October 2020 to coincide with regional and municipal ballots.

"We are happy to have been able to participate in an agreement that defeats violence," said Jacqueline van Rysselberghe, leader of the right-wing Independent Democratic Union, the largest party in President Sebastian Pinera's governing coalition.

- Reform demands -

The unrest that began on October 18 with protests against a rise in rush-hour metro fares has mushroomed into a broader outcry against the status quo, with burning, looting and daily confrontations between demonstrators and police.

The crisis is Chile's biggest since its return to democracy in 1990, leaving 20 dead -- five at the hands of state forces -- and more than 1,000 injured.

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Protesters cite low wages, high costs for education and healthcare and a yawning gap between rich and poor in a country dominated politically and economically by a few elite families.

Demonstrators have demanded greater social reform from the government led by Pinera, who has announced several measures in a bid to assuage public anger.

After weeks of sometimes violent demonstrations, most polls show the protest movement is supported by 75 percent of Chileans.

Even more -- 87 percent, according to a survey by pollster Cadem published this month -- say they favor the protesters' demand for constitutional reforms.

Approved in 1980, Chile's junta-era constitution preserved some powers of the military and established an electoral system that long favored the political right-wing.

Changes in 2005 removed most remaining anti-democratic aspects of the charter, ending the appointment of non-elected senators and allowing civilian authorities to dismiss military chiefs.

"The Constitution of the dictatorship has died," progressive senator and former foreign minister Heraldo Munoz said after Friday's vote.

A few days after Pinera became president last year, his government announced it would not allow the consideration of a bill to amend the constitution that his socialist predecessor Michelle Bachelet had submitted to congress.

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