The Premier League side are ready to pay Messi whatever it takes to reunite him with Pep Guardiola.
Barca are in turmoil, after a season where they surrendered the LaLiga title to bitter rivals, Real Madrid and were thrashed 8-2 by Bayern Munich in the Champons League.
The clause in Messi’s contract that allows him to leave for free at the end of every season expired at the end of May.
But City are now waiting for an indication from the 32-year-old that he will consider leaving the Camp Nou after 16 years.
His current £635 million buy-out clause puts him out of the reach of every club, but Barcelona don’t have the money to finance the squad and may be forced to sacrifice their most precious asset.