Sexually explicit photographs and video of Manaudou, 21, appeared on the Internet and less risque pictures circulated in Italian newspapers, Skynews reported Thursday.
The world champion swimmer is a pop icon in France and is seen as a gold-medal contender at next summer's Beijing Olympics.
Her ex-boyfriend, Italian swimmer Luca Marin, denied releasing the photographs.
The couple allegedly argued during the European short-course championship in Hungary Dec. 15 where Manaudou placed first in the 400-meter freestyle, finishing nearly 3 seconds ahead of Italy's Federica Pellegrini.
Manaudou said the sexually explicit material left her feeling "violated" and the French media expressed outrage over their release.
She angered French fans when she relocated to Italy to be with Marin but was later fired by her Italian club for "attitude problems," Skynews said.