Chile on Monday marked 50 years since the coup d'etat that brought Augusto Pinochet to power, with political divisions over the legacy of his brutal dictatorship on stark display.

Commemorations of the violent US-backed ouster of Marxist leader Salvador Allende still evoke strong emotions, and police fired teargas and water cannons at protesters who vandalized the presidential palace on the anniversary's eve.

Leftist President Gabriel Boric led an event at the palace, known as La Moneda, to mark the historic date, and stressed the need to condemn those who violate human rights "without any nuance."

"The coup cannot be separated from what came after," he said, referring to the 17-year Pinochet dictatorship under which more than 3,200 people were killed or "disappeared" and tens of thousands tortured.

The far-right UDI party issued a statement Monday defending the coup as "inevitable" due to the failures of Allende's political left.

The presidents of Mexico, Colombia, Bolivia, and Uruguay were at the emotional ceremony in Santiago, also attended by Rage Against the Machine guitarist Tom Morello and former Uruguayan president Jose Mujica.

No right-wing representatives attended Monday's event at La Moneda.

Poetry readings and musical performances were interrupted by a minute of silence to mark the moment the bombs started dropping on the palace. Allende committed suicide while troops and tanks closed in.

As night fell, thousands arrived at the national stadium in the capital — once used by Pinochet's regime as a torture center — to place candles in memory of the victims.

Elsewhere, protesters on the outskirts of town prevented the passage of vehicles.

The 1973 coup, in a country seen until then as a bastion of democracy and stability in Latin America, reverberated around the world and underscored covert interference by the United States.

US State Department spokesperson Matthew Miller said Monday that President Joe Biden's government "has tried to be transparent about the US role in that chapter of Chilean history by recently declassifying documents from 1973 as the Chilean government has requested us to do."

'Never again'

Chileans remain deeply divided between those who defend the coup and those who repudiate it, while many feel the anniversary is irrelevant amid economic woes and concerns over rising crime.

A survey conducted by Cerc-Mori in May found that 36 percent of people believe Pinochet "liberated Chile from Marxism" — the highest figure measured in 28 years of polling.

On Sunday, Boric became the first president since the end of the dictatorship in 1990 to attend a commemorative march through Santiago for Pinochet's victims.

But the procession was marred by vandals causing damage to the exterior of La Moneda and the general cemetery that houses a victims' memorial.

Six police officers were injured and at least 11 people were arrested, officials said.

Boric blamed the acts on "adversaries of democracy."

On Sunday night, some 6,000 women dressed in black held a peaceful vigil in the capital under the slogan: "Never again will democracy be bombed," in reference to the 1973 air raids.

Led by Boric, Allende's leftist political heirs are in power in Chile today.

But the far-right Republican Party — Pinochet apologists — emerged the strongest from elections in May for a body tasked with drafting a new constitution to replace the one that dates from the dictatorship era.

Pinochet died of a heart attack on 10 December 2006, aged 91, without ever stepping foot in a court.

Michelle Bachelet, a former leftist president of Chile, told a local radio station Monday the country must "learn from the lessons of the past" at a time when politics "is a little toxic."

She herself was tortured during the dictatorship, as was her father, an air force general who had opposed the coup.

Chile's right-wing opposition has abstained from signing a document affirming a commitment to "defend democracy from authoritarian threats" that has been signed by four living ex-presidents of the South American country.

On Sunday, UN Secretary-General Antonio Guterres said the 1973 coup "was an institutional breakdown that ruptured the bonds of coexistence and marked generations of Chileans, but also inspired many to fight for justice and freedom."

He added: "Today's strong Chilean democracy gives us hope that humanity, united in its diversity, can solve any global challenge."