Me costó encontrarlo, lo puse en el thread de problemas con el partido Barça-Athletic pero seguro que aquí lo lee más gente y queda todo aclarado porque seguro que el tema vuelve a salir.
4.2. Tasks of the clubs
The clubs undertake to guarantee UEFA optimum support in the
implementation of the commercial rights, and to refrain from taking any steps
that would encroach upon the abovementioned rights of the partners. For
UEFA Champions League and play-off matches, the clubs undertake to
observe UEFA’s instructions regarding the exclusive area. In particular the
home club must provide a “clean stadium” by at least the morning of two
days before a match, meaning that no advertising except that officially
authorised by UEFA may be located within the exclusive area.
UEFA, or a third party acting on its behalf, will provide the advertising boards
(at least 90cm high) and be responsible for their installation and dismantling
within two days of the match. The club is responsible for ensuring that the
advertising boards are within the unimpaired range of view of the main
camera.
Reglamento UEFA Champions League 2011/2012