According to a study commissioned by three leading European clubs, the Barcelona forward's value far exceeds his buy-out clause of €250m (£200m).
Professor Gerardo Molina, who wrote the report, said: "There is a club that is practically sponsored by a government [reported to be PSG, though City also fit the criteria] that would be prepared to pay €400m for Leo Messi.
"There are three European clubs that asked us to come up with this study in order to find out how much Messi was worth. We cannot say who the clubs are. The clubs wanted to analyse the viability of a possible transfer for Messi."
Molina added: "Messi is five times more marketable than Cristiano Ronaldo. According to studies, Ronaldo is worth between €150 and 160m. Messi’s buy-out clause is €250m, we believe that figure is obsolete and devalued.
"Right now there is no player in the world of sport that has a greater value than Leo Messi. According to market research in the last five years, Messi is worth €400m."
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