The British government has said that links between the Covid-19 outbreak in Liverpool and the Champions League game at Anfield attended by more than 3,000 Atletico Madrid fans should be investigated.
The match, played on March 11, saw thousands of fans travelling from Madrid despite the city already introducing a partial lockdown amid the coronavirus pandemic.
Matches in Spain’s top two divisions were already being played behind closed doors then.
The last-16 fixture was the last Champions League game played in the UK before the football competition was suspended.
Athletico Madrid defeated Liverpool 3-2 to move into the quarter finals in a game that attracted about 52,000 people.
But the match has been blamed for some of the 246 coronavirus deaths in Liverpool hospitals, and deaths in care homes, which are not included in the government numbers.
Although there is no confirmed link between the tie and the spread of the virus, Britain’s deputy chief scientific adviser, Angela McLean, said it was “an interesting hypothesis” and should be explored.
"It will be very interesting to see in the future, when all the science is done, what relationship there is between the viruses that have circulated in Liverpool and the viruses that have circulated in Spain," Ms McLean said on Monday.
Officials have also expressed regrets that the game was allowed to take place.
This month, Liverpool city council's director of public health, Matthew Ashton, told The Guardian that the fixture should have been called off.
Jose Luis Martinez-Almeida, the Mayor of Madrid, said it was a mistake to allow fans to attend.
“It didn’t make any sense that 3,000 Atletico fans could travel to Anfield at that time,” Mr Martinez-Almedia told Spanish radio station Onda Cero at the weekend.
“I think even at that time there should have been more caution."
Everton boss Carlo Ancelotti revealed last month that Liverpool coach Jurgen Klopp was seething that the game was able to go ahead, calling it a “criminal act”.
Madrid has been one of the worst-affected cities from Covid-19. Spain’s infection cases are the second highest in the world and the country’s death toll is nearly 21,000.