Reuters and Associated Press say they have seen a document filed in Sao Paulo alleging he drunkenly assaulted his accuser at a hotel in the French capital, where he plays for Paris Saint-Germain.
Neymar has so far not commented, but his father and agent, Neymar Sr, told a local TV station in Brazil that the 27-year-old was innocent and had fallen victim to “a trap”.
Neymar Sr has said “WhatsApps and the conversations with this girl” will prove his son is innocent, but said the family were living “difficult moments”.
Neymar is alleged to have met the woman after they exchanged messages on Instagram, leading to his assistant sending her plane tickets on 15 May and the pair checking in to a hotel.
The former Barcelona player, who signed for PSG for a world record £198m, is said to have been “apparently drunk” upon his arrival and became “aggressive” after he and the woman “caressed”.
According to the claims in the police report, Neymar then used “violence” and “practised sexual intercourse against the will of the victim”.
The woman told police about the incident when she returned home to Brazil, having not reported it in Paris because she was “emotionally shaken and afraid to register the facts in another country”.
PSG have not commented on the allegation, nor has the hotel where it is said to have taken place.
Neymar is currently in Brazil, training with the national team ahead of the Copa America tournament this month.