The agent of Porto midfielder Hector Herrera says he can only leave for his buyout clause.
After an impressive World Cup with Mexico, Herrera has been linked with Olympique Marseille, Arsenal and Real Madrid.
Matias Bunge, Herrera's agent, admits Porto have no interest in negotiating terms.
He told TMW: "Hector can leave only if a club pays the €40m of his clause of departure. This is the request of FC Porto."