Scientists and public health experts have warned that the return of fans to Wembley Stadium for the Euro 2020 football final and other mass events under the government’s research programme for England risks further coronavirus outbreaks.

Football fans gathered across central London several hours before Italy beat England in Sunday’s Euro 2020 final after a tense penalty shootout. Tens of thousands travelled to the stadium, with some ticketless fans breaking through barriers to watch the men’s team’s first major tournament final in 55 years.

On Monday the Football Association, the governing body for football in England, said it would work with the police, the Greater London Authority, and European governing body Uefa on a “full review and investigation into the events”.

The final was one of several sports fixtures being held under the UK government’s Events Research Programme, a scheme designed to allow fans to return safely to stadiums after more than a year of games being held behind closed doors.

But there are concerns that football fans, who widely ignored social distancing guidelines as they chanted and set off flares across central London, will fuel exponential growth of coronavirus cases. Although fans with tickets were required to provide proof of double-vaccination or a negative Covid-19 test, checks could not be carried out on those in crowds that gathered across the city or those without tickets who broke into Wembley.

As the teams battled it out in extra time on Sunday night, Maria Van Kerkhove, a senior World Health Organization epidemiologist, tweeted her disbelief at the scenes inside the stadium. She wrote: “Am I supposed to be enjoying watching transmission happening in front of my eyes?” At a press conference on Monday, she added: “The side events, the fan zones, the coming together in populations that are not well vaccinated, without interventions in place, with the Delta variant, can fuel spread.”

On Sunday police failed to prevent crowding in central London and were unable to stop ticketless fans from leaping over barriers to infiltrate the stadium. The Metropolitan Police said officers arrested 49 people and that 19 officers “were injured while they confronted volatile crowds”.

In a statement the FA said: “[T]he behaviour of the people who illegally forced their way into the stadium was unacceptable, dangerous and showed total disregard for the safety and security protocols in place.”

It added that the security and stewarding presence at the final exceeded requirements.

Although the first results from the ERP were deemed to be “encouraging” by public health officials, the nine large sports and entertainment gatherings under scrutiny took place in April and May, when prevalence of the virus was far lower than now. But the UK has one of the most vaccinated populations worldwide, with nine in ten over-50s fully vaccinated.

Martin Mckee, professor of European public health at the London School of Hygiene and Tropical Medicine, told the FT: “While we can quibble forever about the exact impact of yesterday’s events, we know they will accelerate transmission.”

Irene Petersen, professor of epidemiology and health informatics at University College London, said she worried about the virus spreading among fans on public transport, and in pubs and homes where tens of millions more gathered to watch the match on television. “We know that Covid is thriving in close contact where there’s poor ventilation,” said Petersen.

The ERP’s science board is still collecting and analysing data from all the events held under the scheme, including matches at Wembley, according to a person close to the UK’s Department for Digital, Culture, Media and Sport.

Iain Buchan, a professor of public health at the University Liverpool who served as principal investigator for the first stage of the ERP said there was “room for improvement” in the public health messaging around the Euro 2020 final.

“We could do better with big events nationally to get the event organisers and some of the celebrities involved to reinforce what we can all do to protect ourselves, our families and the fans,” he said. He added that he was especially concerned by the “extensive and rowdy” crowds who took part in the “events around the event”.