Mass gatherings should be carefully thought about as Covid-19 restrictions are eased or “many people will look back with many regrets," according to Dr Mike Ryan of the World Health Organization (WHO).
His comments come as England and Denmark are set to play in front of a 60,000-strong crowd at Wembley stadium in London tonight.
At a briefing on Wednesday, members of WHO were asked about mass gatherings and changes to coronavirus restrictions in countries across Europe.
Dr Mike Ryan, executive director, WHO Health Emergencies Programme, said he would not comment on specific events or mass gatherings, but encouraged governments to be "very careful and not disrupt gains made.”
Dr Maria Van Kerkhove, technical lead, WHO Emergencies Programme, said: “Fan zones and sporting events drive transmission by bringing people together.”
She added that the past week had seen a 33% increase in Covid cases across Europe.
Latest UK figures show the number of daily reported cases stood at an average of 27,557 on Wednesday July 7, up 43% on the equivalent figure a week ago.
WHO advised countries to take a “risk management” approach when lifting restrictions.
This involved looking at data on virus cases and transmission rates, avoiding too much social mixing and dealing with social and health measures appropriately.
Dr Ryan said: “The UK has had great success with vaccination.
“Vaccination is meant to take pain, tragedy and suffering from the pandemic, but we are not there yet.”
It was reported on Wednesday that the total number of reported deaths from Covid-19 worldwide has passed four million.