Dutch taekwondo competitor Reshmie Oogink and one member of the team staff have tested positive for COVID-19 in Japan, both Japanese and Dutch media reported on Thursday. Both will go into mandatory 10-day quarantine.

Czech women's beach volleyball player Marketa Nausch-Slukova also tested positive for the virus, Czech Television reported on Thursday.

So far, three Czech athletes at the Tokyo Olympics have tested positive for COVID-19.

On Wednesday, the British delegation announced that the world's No. 1 skeet shooter, Amber Hill of Britain, had withdrawn from the Tokyo Olympic Games after testing positive for COVID-19 in the UK.

The total number of positive cases linked to the Games stands at 87 since July 1, organizers announced on Thursday.

Japanese Emperor Naruhito, who will declare the official opening of the Games on Friday, acknowledged on Thursday the difficulty of preventing the spread of coronavirus during the Olympics, at a meeting with International Olympic Committee (IOC) officials.

"Managing the Games while at the same time taking all possible measures against COVID-19 is far from an easy task," Emperor Naruhito told IOC President Thomas Bach and other IOC members.

(With input from Reuters and Xinhua)