The infected person is a member of one of the foreign delegations, there is no information about the citizenship and gender of the patient.
Fears of coronavirus outbreak at Tokyo Olympics emerged earlier in July, when eight athletes from the Kenya women's rugby team were classified as close contacts after someone from their flight to Tokyo tested positive.
Besides, a member of the Nigerian Olympics delegation also tested positive at Narita airport and was reportedly admitted to hospital.
The Summer Olympics in Tokyo, originally scheduled to take place in 2020, was postponed for a year due to the outbreak of the COVID-19 pandemic.
The event is currently set to take place on July 23 through August 8 and be held without spectators due to the remaining risks of the virus.