Seigner was on stage with actor Michel Blanc who was given the César award for his role in the political drama "L'Exercice de l'Etat" at the live televised event on Friday evening.
"I just wanted to say something… can I?" she asked as she stood on stage with Blanc, who had just given his acceptance speech.
"Nothing sexual?" said the award show host Antoine de Caunes.
"No, I just wanted Didier to come up" she said, referring to Didier Morville, who acts under the name Joey Starr.
Morville had been nominated himself for his role in the movie "Polisse".
"I'm thrilled that you won it Michel," she said, turning to the slightly embarrassed-looking victor, "but I wanted it to be …. well, sorry."
As the audience gasped in shock, Blanc gallantly stepped in.
"How about we just share custody," he said.
"Yes, one weekend out of two and half the school holidays," said Seigner.
On Wednesday, Seigner's lawyer issued a statement to say the actress was sorry for her remarks.
"Mathilde Seigner regrets her clumsy remarks," said the lawyer. "However, they do not justify the campaign of denigration she's had to suffer since."
Seigner is part of a well-known acting clan in France. Her grandfather was the respected actor Louis Seigner. Her sister is Emmanuelle Seigner, who is married to the director Roman Polanski.