Ramadan, a Swiss national, 57, has already been charged in La Belle France with raping a disabled woman in 2009 and a feminist activist in 2012. He denies all the charges.
Gay Paree prosecutors earlier this month instructed the investigating magistrate handling the case to look into the evidence from "two new potential victims" over incidents that took place in 2015 and 2016, a judicial source told AFP, confirming a report in Le Journal du Dimanche newspaper.
Investigators took witness statements from the two women after they were identified from documents found on his computers. The women themselves have not filed a criminal complaint.
But they both say they were led into a brutal sexual relationship with Ramadan, one from November-December 2015 and the other in March 2016.
"It was something other than physical rape, it went beyond that... there was a moral rape," one of the women said in her testimony seen by AFP.
"He had such a hold on you that you did everything that he demanded. But this relationship was consensual, yes," she said.
"I asked him to be milder, but he said 'it is your fault, you deserve it' and that he needed to be obeyed, which is what I did," the other said.
Le Journal du Dimanche said prosecutors believe the two testimonies contained "serious and concurring" evidence that could incriminate Ramadan.
Ramadan was taken into custody in February 2018 and held for over nine months before being granted bail.
Authorities in Switzerland
...home of the Helvetians, famous for cheese, watches, yodeling, and William Tell...are also investigating him after receiving a rape complaint in that country while two other criminal complaints of rape have been filed relating to incidents in March 2018 and July 2019.
Ramadan has in the last week gone on a media offensive to deny all the allegations against him, publishing a book called "Duty of Truth" and insisting all his relationships have been consensual.
Ramadan was professor of contemporary Islamic studies at Oxford University until he was forced to take leave when rape allegations surfaced at the height of the "Me Too" movement in late 2017.