French champions PSG eased to a simple 6-1 victory over the Serbian side on October 3 - with Neymar crashing home an impressive hat-trick at the Parc des Princes.
But in the days leading up to the match, UEFA received a tip off that a senior official at Red Star Belgrade, who has not been identified, along with accomplices, were ready to place a mega bet on their outfit to lose heavily.
L'Equipe reports police in France are now investigating the claims, after the National Finance Prosecutor was alerted by UEFA president President Aleksander Ceferin before the fixture.
Contacted by L'Equipe, Red Star Belgrade President Dragan Dzajic said: “You are the first to tell me about this. I know absolutely nothing about this. This is not possible, this is not true."
A PSG statement said: "It is with the utmost amazement and indignation that we learn the information you are sharing with us today.
"At no time was any club member asked to discuss matters other than those strictly related to the organisation of the match, namely meetings, visits and other official lunches around every UEFA Champions League match."
"The article can harm and bring big damage to our club's reputation and that is why we insist that Uefa and investigators in Serbia and in France investigate the whole story and get the truth.
"Today's technologies and other mechanisms are so improved that it is basically impossible to leave this case unsolved.
"Red Star expects to get the truth at short notice and remove any doubt about our involvement in possible wrongdoing."