On Saturday morning, a member of the team behind the Polish Eurovision Song Contest tested positive for covid-19.
"The person had last been in the arena on Thursday when the entire delegation was able to show negative covid-19 results," the EBU writes in a press release.
Polish artist Rafal and all members of the delegation are now being quarantined pending new test results.
This means that the group will be forced to cancel its participation in Eurovision's opening ceremony on Sunday.
Rapid tests were 48 hours
As a precautionary measure during rehearsals, all persons present in the arena must perform rapid tests for covid-19 every 48 hours. For preventive purposes, all countries have also been allowed to pre-record a live performance in the event that they would not be able to attend the competitions or the final.