Japanese speed skater Kei Saito has become the first athlete to be hit with a doping ban at this year's Winter Olympics in South Korea.

The Court of Arbitration for Sport confirmed that the 21-year-old has left the Olympic Village after testing positive for the banned diuretic acetalozamide.

Saito, who has protested his innocence, was due to make his first Pyeongchang appearance in the men's 5,000m relay on Tuesday.

"I am shocked by this as I have never tried to commit doping," BBC Sport quotes the skater as saying.

"I have been trained in anti-doping. I have never taken a steroid so there is no need for me to mask something, and I never had to drop weight by using this medicine.

"So I have no motivation to use this. I want to prove my innocence but I do not want to burden my team so I accepted this decision."

Saito has been given a provisional suspension from professional skating while an investigation into the positive drugs test is carried out.