The chief of the Tokyo Olympics accepts athletes are "probably very worried", after a Games-related organiser became the first person to test positive for Covid-19 in the athletes' village.

The case, who is now quarantining in a hotel for 14 days, is one of 15 Games-related cases reported on Saturday.

The organiser tested negative upon arrival in Japan before returning a positive test in the village screening.

The organisers have previously said the village "must be the safest place".

"Athletes who are coming to Japan are probably very worried. I understand that," said Games chief Seiko Hashimoto.

"That is the reason why we need to make full disclosure.

"We are doing everything to prevent any Covid outbreaks. If we end up with an outbreak we will make sure we have a plan in place to respond."

The Games, postponed for a year due to the global pandemic, is being held mostly without spectators and under tight quarantine rules, with Tokyo currently in a state of emergency, until at least 22 August, amid rising Covid-19 numbers.

Athletes, who will be tested daily, are starting to arrive in Tokyo, with the Olympics running from 23 July to 8 August.