The German FA (DFB) has come under fire for covering up an anti-racism banner during Sunday's Under-19 Championship final between Hannover 96 and TSG Hoffenheim.
Hoffenheim won the match at Hannover's HDI-Arena 5-0, but controversy was sparked when, as well as covering up advertisements in the stadium, officials also covered the "96 Fans Against Racism" banner that has been on display since 2005.
Muller was referring to last month's controversial "neutralisation" of a "No football for fascists" banner during a German team training session prior to a friendly match against Poland.
DFB general secretary Helmut Sandrock said: "We have explained to the fans that the stadium received a uniform look and, regrettably, the banner was also covered."
He said German football's governing body had already honoured the anti-racism work done by Hannover fans, but Muller added: "In future, the DFB should contact fan liaison officers to find out if there are any banners that should not be covered."
Last month, the DFB argued that it wanted all games to be free of any political statements.