Goal reported on Tuesday morning that City intend to sign the 23-year-old centre-back in January by triggering his €65 million release clause.
It can now be revealed that Laporte has agreed a deal in principle to join City and has informed Athletic of his decision to leave before the end of the winter transfer window.
Further developments are expected on Wednesday and it is believed that the transfer will develop quickly now that the France international has informed his boyhood club that it is his desire to join City.
He had reached the same conclusion in the summer of 2016 but eventually pulled out of the deal at the last moment, a move which angered the Blues.
That anger has subsided over the past 18 months and the club are now satisfied that he is committed enough to a move to the Etihad Stadium to pursue him once again.
It is believed Athletic will not negotiate any fee lower than Laporte's buy-out clause, and City are willing to pay that amount in the coming days.
The Blues also want to sign Shakhtar Donetsk midfielder Fred this month and are in negotiations with the Ukrainian side.
Additional reporting by Sam Lee.