A Chilean taekwondo competitor has become the first athlete to withdraw from the Tokyo Olympics after testing positive for Covid-19, officials said.

Fernanda Aguirre had travelled to Japan from Uzbekistan, where she had been preparing for the Games, but tested positive on arrival.

"(She) is asymptomatic and in good health, but unfortunately will not be able to compete because the Japanese authorities impose a 10-day quarantine," a Chilean Olympic committee statement said on Tuesday.

Aguirre has been moved to an isolation facility, as has her coach.

The 21-year-old, who won a bronze medal at the 2019 Pan American Games, said on social media she was "destroyed and very sad".

There have been 79 Games-related coronavirus cases so far at the Olympics.

Meanwhile 31-year-old skateboarder Candy Jacobs, who was due to compete in the women's street event on Monday, is also out after testing positive.

Jacobs is the fourth athlete to test positive in the Olympic Village, after South African footballers, Thabiso Monyane and Kamohelo Mahlatsi and Czech beach volleyball player Ondrej Perusic, all of whom could conceivably still compete once they have completed their 10-day quarantine.

Jacobs told Dutch media: "I'm devastated. We were ready for the Games, I feel fit and now it's over."