Euro 2016 matches in France could be played behind closed doors because of the terrorism threat, a UEFA official has claimed.
Giancarlo Abete, vice-president of the governing body's Executive Committee, made the comments following the atrocities in Brussels yesterday which have left 34 people dead.
UEFA, however, have said there are "no plans" for behind closed doors fixtures.
Security concerns ahead of the continent's major football tournament were ramped up following November's terror attack in Paris, which saw 130 people killed in the French capital.
One of the targets in the 2024 Olympic bid city was the Stade de France - which is due to stage matches at the European Championships, including the final on July 10 - with UEFA saying yesterday that they would continue to "monitor the level of risk" ahead of the tournament.
Abete, a former President of the Italian FA, applied more urgency to the situation by suggesting some matches could take place without fans.
The tournament is due to be played between June 10 and July 10 in 10 French cities.
"We can't exclude the possibility of playing behind closed doors, as we cannot exclude terrorism," Abete told Italian radio station Radio24.
"If we talked about potentially cancellable [sic] games, such as a friendly or a competitive match, they could be moved to another date.
"Obviously this would not be the case.
"But we are talking about games which are staged for June whereas, today, we are going through a very urgent emergency."
In a statement responding to Abete's comments, UEFA said: "We are confident that all security measures will be in place for a safe and festive Euro and therefore there are no plans to play matches behind closed doors.
"However, we are nevertheless working on contingency plans and on multiple scenarios around crisis situations since we take the security of all participants very seriously."
One football fixture has already been moved due to the Brussels attacks, with Belgium's friendly against Portugal on Tuesday (March 29) switched to the latter country.
It was due to take place at the King Baudouin Stadium in the city but has been moved to Leiria for "safety and precaution".
The attacks in Brussels, which remains on a high state of alert, targeted the Belgian capital's Zaventem airport and the Maelbeek metro station.
They followed the arrest of Salah Abdeslam in Brussels five days ago, who was wanted in connection with the Paris attacks.
The sporting world has paid tribute to Brussels with International Olympic Committee (IOC) President Thomas Bach describing what happened as "odious".
Further sporting events, such as cycling's E3 Harelbeke, a men's one-day World Tour race on Friday (March 25), could yet be cancelled.
A Women's World Tour race, the Gent–Wevelgem, is due to take place on Sunday (March 27).
The Islamic State group has claimed responsibility for the Brussels attacks.