Six members of boxing teams who attended an Olympic qualifying event in London in March are said to have contracted coronavirus.
The Turkish Boxing Federation said two fighters and a coach tested positive since returning from the event.
Marko Marovic of the Croatian Boxing Federation also claims a fighter and two of its coaches have the disease.
He said: “Our epidemiologist says they were most probably infected during [the] Tokyo 2020 qualifier.”
Marovic, secretary general of the Croatian Boxing Federation, added: “Our first concern is the health of our boxing family. We are still praying that everything ends well and there will be no other positive tests.”
He said both Croatian coaches and the fighter were “stable” and in quarantine.