Benedito is concerned that Messi has not put pen to paper on a new contract agreed over a month ago.
He told Onda Cero: "Messi is the most important player of the club and he has still not prolonged.
"The case of Messi may be worse than that of Neymar because he will be free from January 1st. Messi has always wanted a competitive team and the situation is worrying.
"(Josep Maria) Bartomeu announced that Messi had signed his extension in June but this is not true. If Messi has not yet prolonged, it is because it is not clear to him."