Organized crime launders an estimated $140 billion through sports betting each year, according to a new international report.
The study was conducted by the International Centre for Sport Security and the University of Paris I. Researchers concluded that 80% of sports betting worldwide is conducted illegally.
"The rapid evolution of the global sports betting market has seen an increased risk of infiltration by organized crime and money laundering," said Chris Eaton, an official at the security center. "Alongside this, the transformation of the nature of betting, with more complex types of betting ... has made suspect activity even harder to detect."
Soccer and cricket lead all sports in terms of illegal activity, the report said, with most of this betting taking place in Europe and Asia.
Criminal activity is thought to increase the risk of fixing.
"There is a desperate need for well-designed criminal laws specific to the manipulation of sport," said Laurent Vidal, chairman of the research program.