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Eliaquim Mangala may have cost Manchester City a staggering £42MILLION, according to a leaked transfer document, writes Rob Pollard of the Manchester Evening News.

Website Football Leaks claim to have got hold of a copy of the transfer contract that took the defender to City in 2014.

It shows that the club paid a lot more than the £32million they originally claimed they had shelled out for him.

According to the document, which appeared online on Wednesday, selling club Porto only owned 56.67 per cent of Mangala's economic rights.

The remainder was split between The Doyen Sports Investment Limited, who owned 33.33 per cent, with another 10 per cent belonging to an Austrian marketing company.

(Image: Reuters)

City had to pay close to £24m for Portuguese giants Porto's share alone, meaning the remainder of the deal took the total to £41.4m.

The club haven't commented on the emergence of the document.

With Mangala still struggling for consistency since his switch 18 months ago, his future remains in doubt.

There were suggestions the defender was offered to Valencia on a two-year loan deal as part of the agreement to bring Nicolas Otamendi to the Etihad in August - a move the player rejected.

(Image: Action Images via Reuters / Paul Childs)

Should City try to offload him this summer, they would be unlikely to recoup anywhere near the fee they paid for him.

This leak follows one earlier in the week, which claimed to show in detail how much Manchester United paid Monaco for Anthony Martial - including details of a Ballon d'Or clause.

(Image: Rex)

And details of defender Mehdi Benatia's Bayern Munich salary appeared to have been shared online when an image apparently of his payslip was leaked on messaging service WhatsApp.

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