A French envoy has said her country did profit from slavery as it officially commemorates the victims of the trade for the first time.
Campaigners have been pushing for a commemoration for years
"It profited from the commerce in human beings... ripped from the African homeland," Junior Co-operation Minister Brigitte Girardin said in Senegal.
She was visiting a notorious slave island off the coast of Senegal.
In Paris, President Jacques Chirac said facing up to the colonial past was a "key to national cohesion".
He opened an art exhibition in Paris's Luxembourg Gardens while other cities and venues around France held their own ceremonies for Slavery Remembrance Day - the first such event in an EU state.
Wednesday's day of commemoration was ordered by Mr Chirac, on the fifth anniversary of the passing of a law by the French Senate recognising slavery as a crime against humanity.
Hundreds of thousands of slaves were taken by French ships from Africa to plantations in the Caribbean before France banned the practice in 1848.
It was, Mr Chirac said, an "indelible stain on history".
Ms Girardin visited Goree Island along with Senegalese President Abdoulaye Wade.
FRENCH SLAVE TRADE
France mainly used slaves, taken from Africa, in its Caribbean colonies
France estimated to have shipped 1,250,000 slaves
France was Europe's first country to abolish slavery, in 1794
But it was revived by Napoleon in 1802, and only banned for good in 1848
African slaves were shipped to the Caribbean from Senegal, a former French colony.
"Coming to Goree Island is paying homage to the long succession of anonymous victims who, over the centuries, suffered slavery and struggled for its abolition," said Ms Girardin.
"The greatness of a nation resides in its capacity to bear full responsibility for the darkest periods of its history," she added.
President Wade rejected the idea of compensation for victims of slavery.
"There are some things that have no price," he said.
"You could give me the Bank of France and contents of the United States' Fort Knox but that would not undo what we have endured."
President Chirac said he was committed to fighting modern forms of slavery, allowing companies that knowingly use forced labour anywhere in the world to be prosecuted in French courts.
Jacques Chirac and actor Jacques Martial toured a new exhibition
"This first commemoration isn't the end, it's a beginning," he said.
"It's the necessary affirmation of the memory of slavery shared by all French people, whatever their origin."
The city of Nantes on the Atlantic coast, where many of France's slave ships originated, held a minute's silence.
Museums and libraries in Paris opened special events showing off contemporary manuscripts and artefacts.
"It was imperative that slavery be given a place in our collective memory," said Marcel Dorigny, a history professor who helped institute Slavery Remembrance Day.
"French people who are the descendants of slaves have felt marginalised - forgotten by history."
But some critics said the commemoration was not enough, and that the government's current policies were still alienating racial minorities.
French MPs were on Wednesday examining tough new immigration legislation limiting entry to foreigners.