The Mirror says Etihad chiefs fear that two of their most prized assets have had their heads turned by Paris Saint-Germain and Barcelona, respectively.
Toure has insisted that it would be an honour to play for the French champions.
And Aguero's father, Leonel del Castillo, has given an interview in Spain in which he spoke about his son's desire to join Barcelona.
That has prompted City to remind all of their players that they have a contractual obligation not to speak in depth about club issues while they are away on international duty.
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