Six-time Olympic gold medalist Viktor Ahn on Monday announced his retirement from short-track speedskating, citing several lingering injuries.

The South Korean, who switched allegiance to Russia in 2011 and won three gold medals and a bronze at the 2014 Sochi Olympics, said in a letter carried by Russia's RIA news agency that he did not think his body could handle another season.

He said knee problems and other injuries were making it difficult for him to compete.

"In addition to constant knee pains, other injuries have also appeared," he wrote. "It is becoming more and more difficult to keep fit, so I decided that it was time to leave sport."

Born in South Korea, Ahn won three gold medals and a bronze at the 2006 Turin Games for his native country but was passed over for Vancouver four years later due to a knee injury and after falling out with his country's skating union.

The 34-year-old represented Russia for the rest of his career.

Ahn was left off the list of Russian athletes eligible to compete at the Pyeongchang Winter Games in 2018.

The International Olympic Committee (IOC) had banned Russia from Pyeongchang over "systematic manipulation" of the anti-doping system at the 2014 Sochi Olympics, but left the door open to athletes with no history of doping to be invited to compete as "Olympic Athletes from Russia."

Ahn, who was never publicly implicated in any doping cases, decried his exclusion from the list of eligible athletes, saying he had always complied with anti-doping rules.

He had previously announced his retirement in September 2018, but returned for the 2019-2020 World Cup season.