The Rwandan businessman alleged to have been the main financier of the 1994 genocide has appeared before a public prosecutor in Paris.
Félicien Kabuga, 84, arrived at the court under heavy police protection.
He was arrested in a Paris suburb on Saturday, where he was living under a false identity.
It is expected that he will be tried by a UN tribunal.
A group which supports victims of the genocide said it was considering legal action to determine how Mr Kabuga had managed to live in France for so many years without being caught.