Finnish health authorities have detected a spike in coronavirus cases that has been traced to soccer fans returning from neighboring Russia following European Championship matches in St Petersburg.

The Finnish Institute for Health and Welfare urged all passengers who have traveled from St Petersburg to Finland by any bus company to apply for a coronavirus test.

Any bus or minibus may have been exposed, the institute said.

Finland played two of its Euro 2020 group games in St Petersburg, facing Russia on June 16 and Belgium on Monday. At least 2,000 Finns are estimated to have traveled to the city for those matches.