"I find it surprising, shocking, that the question of rape did not affect the choice," Women's Rights Minister Laurence Rossignol said on Friday, referring to an accusation in 1977 by 13-year-old Samantha Geimer that Polanski drugged and raped her after a photo shoot.
The world-famous director, now 83, spent 47 days behind bars in the US back then but fled the country when he was released on bail.
Since then Geimer has dropped the charges after a financial settlement but Polanski, who was born in France to Polish parents, is still subject to an international arrest warrant.
In 2003 he was unable to pick up a best director award at the Oscars and in 2014 he had to pass on receiving a prize at the Locarno festival in Switzerland.
US international warrant
Polanski spent 10 months under house arrest in Switzerland in 2009 before an American extradition order was rejected and last October Poland's supreme court confirmed a lower court's rejection of extradition.
Rossignol on Friday slammed the Césars organisers' choice, which was announced on Wednesday.
It was a sign of "what feminists call the rape culture in which we live", she said.
An online petition to scrap the invitation had collected 42,000 signatures by midday Friday and the Osez le féminisme (Dare feminism) group has called for a demonstration outside the ceremony at Paris's Salle Pleyel concert hall on 24 February.
The César committee was "thumbing its nose to the many victims of rape and sexual assault", Osez le féminisme's Claire Serre Combe said on Thursday, slamming the "social tolerance that still exists on the subject of rape in France".
Filipetti defends Polanski
Not everyone agrees.
Former culture minister Aurélie Filipetti defended the choice of "a very great director".
"This is something that happened 40 years ago," she commented on Thursday. "We can't bring up this affair every time."
And Césars committee member Alain Rocca said the row was an example of the "post-truth dynamic" that led to the election of US President Donald Trump.
The favourite to win the most prizes at this year's Césars is Elle, which won best foreign film at the Golden Globes in Los Angeles earlier this month.
Starring Isabelle Huppert, who was named best actress there, it is about a rape victim's revenge on her assailant.