Authorities in Tokyo have reported the first apparent community transmission of the coronavirus Omicron variant in the Japanese capital.

Tokyo Metropolitan Government officials say the infected person is a doctor who works at a clinic in Tokyo. They say the case, confirmed Friday, is the first known to involve an individual with no recent record of overseas travel, and whose infection route is unclear.

The officials say a total of five people from the clinic and the person's household have been identified as close contacts, but all have so far tested negative for the virus.

They say none of the clinic's patients are deemed close contacts because the doctor wore both a face guard and mask, and thorough anti-infection measures were in place.

Tokyo Governor Koike Yuriko told reporters that the case is believed to have been community-acquired. She said it is vital to strengthen testing, so that people who are positive can be treated and isolated quickly.

Koike also urged people who are experiencing a cough, fever or other symptoms to consult with a doctor.

Officials in Tokyo reported three other Omicron cases on Friday, all of which involved people returning from overseas. They say two shared flights with people who were confirmed to have been infected with the variant earlier.