Sporting Lisbon chief Bruno de Carvalho has called for third-party ownership to be regulated, describing the practice as a "menace".
Sporting president Carvalho was speaking about the issue at the Soccerex conference in Manchester after being quizzed about Marcos Rojo's transfer to Manchester United.
Rojo's move was a drawn-out affair as the defender was part-owned by the Doyen Sports agency, who were embroiled in a row with Sporting over the player's transfer fee.
An agreement was eventually reached, but Carvalho believes the time has come for third-party ownership to be regulated or scrapped altogether.
"The funds like they are right now are a menace to sports and for football," he said. "Nobody can run a club with five or 10 or 20 per cent of a player.
"We need to work hard, we need to sell players and to buy players.
"When I began in football my idea was to regulate the [investment] funds because it is a way that clubs can arrange a financial solution.
"So I think that the main issue is that the ones that needed to didn't make the regulation and now it is a monster.
"We are in the same line as UEFA and FIFA [over third-party ownership] but what I want is for them not only to say but to do something. Say we are going to put rules that make everything fair because nowadays football is not fair."
Sporting face the possibility of a court case with Doyen, who claim that the Primeira Liga side have reneged on terms in Rojo's contract.
However, Carvalho stated his belief that the agreement was void, adding: "It was invalid. That contract means manipulation. It means engagement with the management [of the club]. It's not a contract. It's null."comments