Neymar put PSG 2-0 up before scoring the final goal of the game
French authorities are investigating potential match-fixing in Paris St-Germain's 6-1 Champions League win over Red Star Belgrade this month.
An official at the Serbian club placed a bet of almost 5m euros (£4.3m) that Red Star would lose by five goals, French newspaper L'Equipe has reported.
The French National Finance Prosecutor (PNF) is investigating the claims after being alerted by Uefa.
In a statement, PSG expressed their "amazement and indignation".
They added: "Paris Saint-Germain reiterates its commitment to a fundamental principle of sport, that of the integrity of competitions and therefore refutes any form of practice that could call into question that integrity."
BBC Sport has contacted Red Star Belgrade for comment.
Brazil forward Neymar scored a hat-trick and Edinson Cavani, Angel di Maria and Kylian Mbappe also netted at Parc des Princes in Paris on 3 October.
Former Germany international Marko Marin scored a second-half goal for Red Star.
Source: bbc.com