City are desperate to beat rivals Chelsea and Manchester United to the signature of the highly rated defender, and are understood to be willing to match the club record fee they paid to sign Sergio Aguero to land him before the close of the transfer window.
However, sources in Portugal claim Porto president Pinto da Costa is desperate to keep hold of the French defender, and will not sanction his departure this month.
The club are reluctant to sell the 22-year-old this month, and would be more open to the possibility of a summer transfer.
Either way, Porto are being forced to make a decision on the centre back’s future, and senior officials are expected to hold talks with Mangala’s agent over the next 24 hours.
City boss Manuel Pellegrini is yet to do any January business, but has identified a new centre back as his top priority.
Any deal to sign Mangala before Friday’s deadline would likely see Joleon Lescott leave the Etihad, with West Ham, Fulham and Aston Villa all reportedly interested in the England defender.