“Her breast’s exposed because she’s feeding the people; she isn’t wearing a veil because she’s free,” he said.
But opponents were quick to seize on his remarks as the race hots up ahead of next year’s presidential elections.
One historian said his use of Marianne as a feminist symbol was “moronic”.
Mathilde Larrere, an expert on the French Revolution, said Marianne was an allegory and the use of her naked breast “just an artistic code” and nothing to do with femininity.
The issue of the full-body swimsuit, known as a “burkini”, has overshadowed French politics in the wake of the militant attack on Nice in July. As campaigning kicks off for next year’s presidential election, Republican candidate Nicolas Sarkozy has called for the swimsuit to be banned.
Mr. Valls last week defended the right of local mayors to impose beach bans, although France’s top administrative court has said the bans breach fundamental freedoms.
And, addressing a Socialist Party rally attended by several ministerial colleagues, he said the French had to reclaim patriotism in the face of Islamist totalitarianism, insisting there should be no compromise on the role of women.
But when he invoked Marianne, Social Affairs Minister Marisol Touraine and Education Minister Najat Vallaud-Belkacem did not applaud.
Green politician Cecile Duflot said the prime minister’s remark was comical because Marianne’s head was covered with a Phrygian cap, another symbol of the French Revolution. She shared several images on social media from a National Assembly exhibition, including one describing Marianne as “a little part of all of us”.
Mathilde Larrere set out in a series of tweets why the prime minister had been wrong to invoke Marianne to support his argument.