The Euro 2020 host cities of Munich, Rome, Bilbao and Dublin have been given an extension until April 19 to provide details on allowing fans into games to remain part of the tournament.
The other eight cities across Europe have confirmed they will allow crowds at stadiums as coronavirus restrictions are eased.
The tournament is due to open in Rome on June 11 and finish with the final at Wembley on July 11.
But Munich, Rome, Bilbao and Dublin could be cut from the plans and the games awarded to other countries if UEFA cannot be sure fans will be permitted.
