TORONTO (REUTERS) - The one-year postponement of the 2020 Tokyo Olympics could open the door for convicted drug cheats to compete for medals, an issue that will need to addressed, United States Anti-Doping Agency (Usada) chief Travis Tygart said on Tuesday.

"This was an issue raised on a call of national anti-doping agencies from 21 countries today," Tygart told Reuters.

"It is one of many complex issues that will have to be thought through and determined now that the Games have been postponed."

Currently, there is no exception to extending an anti-doping sanction for postponed events if the athlete or coach has served their ban when the competition takes place.

The World Anti-Doping Agency (Wada) did not immediately respond for comment.

The doping question is sure to be one of many for the International Olympic Committee (IOC), Tokyo organisers and Wada to address after IOC president Thomas Bach and Japanese Prime Minister Shinzo Abe agreed on Tuesday that the Games needed to be delayed a year due to the threat posed by the coronavirus outbreak.

If an athlete has served his or her ban and is denied a chance to qualify for an Olympic spot, it is almost certain such a ruling could be challenged in court. While anti-doping rules cannot be changed retroactively, the updated Wada Code comes on line in January 2021 which could be applied and impact suspensions.