FIFA fined Portuguese league leader Porto 50,000 Swiss francs ($50,000) on Tuesday for allowing Malta-based investment fund Doyen to influence the club's transfers.

FIFA's disciplinary committee determined that Porto "entered into contracts that enabled the third party to have an influence on the club's independence and policies in transfer related matters," the governing body said in a statement.

FIFA named the third party as Doyen Sports Investments in response to questions from The Associated Press.

Porto was also found to have failed to provide correct data in FIFA's Transfer Matching System.

Doyen has tried to challenge FIFA's ban on third-party ownership of players. It was introduced in 2015 to protect the integrity of football to prevent investing forcing transfers to make a profit.

The third-party investment model was most popular with agents, investors and clubs in Latin America, Spain and Portugal. They argue it let clubs sign players who otherwise cost too much.