UEFA, the governing body of soccer in Europe, has asked the Serbian Football Association (FSS) to investigate alleged match-fixing.
FSS spokesman Milan Vukovic said in an April 11 statement that "we have received certain information from UEFA suggesting possible irregularities pointing to breach of integrity in some games."
He added: "The FSS has opened proceedings but at this time we cannot reveal more details. We will inform the public about our findings in due course."
Serbia's Sport Klub television reported that UEFA had tracked "enormous" bets that were placed on two matches played in March.
Sport Klub added that UEFA tracked betting patterns in both Europe and Asia that included large sums placed on final scores during live betting.
"Players on two teams gave advantage to their opponents, thus securing huge profits to people who made bets," Sport Klub said.
