Two members of a Ugandan group that arrived in Japan on Saturday (June 18) have now tested positive for COVID-19.

A team coach was isolated after testing positive upon arrival at Narita International Airport, east of Tokyo.

The entire delegation and a city official were deemed close contacts and were asked to remain in their hotel and refrain from training until July 3.

A second positive was then announced on Wednesday (June 23).

Kyodo News has reported that the team member to have tested positive on arrival was found to have had the Delta variant.

The Delta variant is thought to be between 40 to 60 per cent more transmissible.

Tokyo 2020 President Seiko Hashimoto has reportedly said organisers will seek to further tighten its countermeasures against COVID-19 before next month's Olympic Games.

Uganda's men's rugby sevens team were also hit by COVID-19 cases before the Olympic repechage tournament in Monaco last week.

The team were forced to withdraw "following a number of positive COVID-19 results determined during scheduled arrival testing".

The team was quarantined on arrival by authorities in Monaco on June 12.

The Ugandan Rugby Union has now confirmed one of the team members, James Odong, has gone missing.

Odong reportedly arrived on June 16.

His disappearance was discovered when the team were due to be retested at the end of their isolation periods.

"It has been brought to the attention of the Uganda Rugby Union Executive Committee that one of the players, James Odong, has been missing from the hotel room where they had been placed for isolation as a measure to control the spread of COVID-19," a Uganda Rugby Union statement read.

"James travelled on June 16 and on arrival they had to undergo a compulsory isolation in the designated tournament hotel.

"On completion of self-isolation on June 19, they were to undergo another COVID-19 test at a venue outside the hotel.

"James Odong did not turn up for the test and when the team members returned to the hotel, he was not in his room or hotel complex.

"The incident was brought to the attention of the team manager who immediately informed the tournament organisers.

"James is in possession of all his valid travel documents with a valid visa, which expires on June 26.

"Uganda Rugby Union takes discipline very seriously and this matter is being dealt with accordingly.

"We have handed over the matter to the relevant security agencies in Monaco and will cooperate with them, the tournament organiser, the French Embassy, National Council of Sports and any other authority to assist with the conclusion of this matter."