Mexico City - Mexico City Mayor Marcelo Ebrard launched Thursday the commemoration of the 40th anniversary of the Tlatelolco Massacre by setting the Mexican flag at half-mast on the site of the violent repression of students in 1968.

During the ceremony at the Plaza de las Tres Culturas square in the Tlatelolco neighbourhood of Mexico City, people demanded that the truth about the events of October 
2, 1968 - when scores of people died in the repression of demonstrators by police and Army forces - be revealed.

The attack came on the eve of the 1968 Olympics in Mexico City, amidst a mood explosive with protests against a heavy-handed government. The dead were victims of the Mexican government's attempt to squelch the protests before the games opened.

Buoyed by the worldwide student protest movement, tens of thousands of students in Mexico City marched to the open Plaza de las Tres Culturas, in the Tlatelolco neighbourhood, hoping to catch the international spotlight before the games.

Survivors of the massacre say that the exact number of dead is not yet known. The authorities have admitted 24 dead, while other sources claim that the figure was over 
300.

The official version says that police and military officers surrounded the square in armoured vehicles and fired machine guns because they were allegedly fired upon by student snipers from the high buildings in the area. However, experts dispute that account.

Remembrance acts planned include a series of cultural events and a demonstration that is set to cover the same route as that of 1968, to end with a rally at the Plaza de las Tres Culturas.

The summer Olympics were held October 12 to 27 that year. (dpa)