MEXICANS commemorated the 50th anniversary of the Tlatelolco massacre yesterday, demanding an investigation to reveal the truth about the atrocity, which has been branded a state crime.

Protests and marches took place across the country in memory of those who were killed and disappeared after Mexican forces opened fire on those gathered to condemn the authoritarian government of Gustavo Diaz Ordaz on October 2 1968.

Around 300 people were killed by state forces, including the army, the secret police, the federal security directorate and the state-sponsored paramilitary group known as the Olimpia Battalion, as they protested in the Tres Culturas Square in Mexico City.

The real figure is unknown as many bodies were taken away and dumped that same night.

Hundreds of people were jailed and tortured with reports of disappearances as the authorities clamped down on dissent in the run-up to the Olympic Games in Mexico City.

The massacre took place after the National Strike Council — formed after attacks on student protesters at two universities — called a peaceful march from Tlatelolco to Zocalo.

However the route was blocked by around 5,000 soldiers prompting organisers to cancel the march and hold a rally inside the Tres Culturas Square.

Adela Gonzalez, who helped organise the protest, explained how security forces opened fire on those who had gathered in the square.

“When I was introducing the second speaker a helicopter flew over and released three flares, two green, and one red. Immediately after, shots were heard and I saw people starting to fall to the ground.”

The Tlatelolco massacre was designated a crime against humanity in 2005, but only one person has been charged. Luis Echevarria Alvarez, who headed Mexico’s intelligence agency at the time, was freed after a period of house arrest due to his age.

Declassified documents exposed the role of the US, with the CIA claiming, without evidence, that the growth of the student and workers’ movements amounted to a “communist plot” backed by Cuba and the Soviet Union.

It supported the severe repression by the authoritarian Diaz regime, which led to the killings and disappearances.

Mexico’s President-elect Andres Manuel Lopez Obrador promised last week that the army would never again be used to oppress the people.

The families of the victims of the Tlatelolco massacre demand an independent investigation to reveal the truth and bring justice for their loved ones.