The peaceful march of between 20,000 to 30,000 demonstrators by the Algerian national liberation front (FLN) on October 17th 1961 had been organized to protest against a curfew that had been imposed on October 5th during the fight for independence in Algeria.
The demonstration became a scene of carnage after the Paris police chief at the time, Maurice Papon, gave orders for the demonstration to be halted.
Police beat and opened fire on protestors with many bodies being thrown over bridges into the river Seine. Other demonstrators were rounded up and taken to detention centres where they claimed of being subjected to torture and starvation.
The first official estimate was of three deaths and 64 injured. A report in 1998 however put the number of deaths at a minimum of 32. Many historians believe the true figure is more likely to be between 50 and 200, perhaps even more.
Protestors renewed their demands on Monday that the deaths be recognized by France as a "state crime".
The newly-elected Socialist nominee for the 2012 presidential elections, François Hollande, chose one of the commemorative events to make his first public appearance as the official candidate on Tuesday.
"I wanted to show my solidarity with the children and grandchildren of the families who were bereaved by this event," he said.
He threw a red rose into the river Seine from a bridge in the northern Paris suburb of Clichy where protestors are believed to have died and later unveiled a commemorative plaque.
The government continues to refuse to apologize for the events.
"France has to face up to its past but should certainly not apologize," said the interior minister, Claude Guéant.
A series of stamps were issued by Algeria's post office on Monday to commemorate the massacre. The stamps show men beating people to death and throwing their bodies into a river Seine that is running red with blood. The Eiffel Tower is shown clearly in the background as well as the flag of Algeria.
The war was settled in July 1962 when the FLN won independence for the country.