* CAS reduces Koga's four-year suspension to two years
* Koga's supplements may have been contaminated (Adds details, quotes)
Aug 2 (Reuters) - Japanese Junya Koga's four-year suspension for an anti-doping rule violation has been reduced to two years after it was found that his supplements may have been contaminated, the Court Of Arbitration for Sport (CAS) said on Friday.
Koga, a gold medallist in the world championships in 2009 (100 metres backstroke) and 2016 (50 metres backstroke), tested positive in March last year for ostarine and ligrandrol, which are on the World Anti-Doping Agency (WADA) prohibited list.
Koga was handed a four-year ban until March 2022 by the International Swimming Federation (FINA) before the 32-year-old filed an appeal in October last year at CAS, who amended FINA's original decision.
"In June 2019, the parties informed the CAS that having agreed that contaminated supplements were the most likely source... of both the ostarine and ligrandrol found in Junya Koga's samples, they had signed a settlement agreement," CAS said in a statement.
"The athlete shall be sanctioned with a period of ineligibility of two years, commencing on the date of provisional suspension on 15 May, 2018. The period of ineligibility shall therefore end on 14 May, 2020 included."
However, Koga's return to competitive swimming looks to have come too late for him to earn a berth at the Tokyo 2020 Olympics, with Japan's Olympic trials set to be held in April. Koga was in Japan's team at the 2016 Games in Rio de Janeiro. (Reporting by Rohith Nair in Bengaluru; Editing by Ken Ferris)