Rio Olympic relay swimmer and 2009 world champion Junya Koga is set to be issued a four-year ban by a FINA doping panel for violating anti-doping rules, sources familiar with the matter said late Monday evening.

Should the sport's ruling body announce the decision, the 31-year-old Koga, who said in a hearing in late August that the positive test resulted from taking dietary supplements, will be shut out of the 2020 Tokyo Olympics.

According to sources, Koga sought a reduction in sanction at the hearing before an impartial panel in late August, but his request was rejected. He claimed he did not act intentionally.

The swimmer could still appeal the decision to the Court of Arbitration for Sport (CAS) and have his doping ban overturned or reduced.

                                                          (Junya Koga)

Koga, gold medalist in the men's 100-meter backstroke at the world championships in 2009, missed out on a berth at the 2012 London Olympics but competed in the 4x100 freestyle relay in Rio.

In March, he failed two drug tests for banned muscle-building substances and was kicked off the national team.