TOKYO - One of the alternate, or replacement, gymnasts for the U.S. team has tested positive for the coronavirus, but the main team has moved to separate accommodation and is continuing preparation for the Olympics, USA Gymnastics said on Monday.

A Japanese official had earlier said one member of the U.S. gymnastics delegation in her teens had tested positive and had one close contact, but declined to give further details.

"One of the replacement athletes for the women's artistic gymnastics team received a positive COVID test on Sunday, July 18," USA Gymnastics said on Twitter.

It added that the local government had determined that the athlete, whose name wasn't given, and one other replacement athlete needed to be subject to further quarantine, so the rest of the team has moved to alternative accommodation and will continue preparing for the Games.

"The entire delegation continues to be vigilant and will maintain strict protocols while they are in Tokyo," it added.

Star gymnast Simone Biles is 24, and two of the main team members, Sunisa Lee and Grace McCallum, are both 18.

Sunisa Lee late on Monday posted a video on Instagram showing her and three team members smiling and waving their accreditation, with the caption "Tokyo bound." Still later, she posted a photo showing her and the others standing in front of the Olympic Village.

Multiple Japanese media reports said that a simple saliva screening test had flagged the athlete concerned as a suspected positive on Sunday, and it was confirmed with a more detailed PCR test on Monday.

They added that this person and one close contact were remaining at the hotel in the city where they trained, just east of Tokyo.

The Olympics, postponed for a year due to coronavirus, open on July 23 and the gymnastics competitions start on July 24. The women's qualifying rounds begin July 25.