Sergio Aguero broke a rib in a car crash in Amsterdam last week and initial reports from City's doctors suggested that he would be sidelined for two to four weeks.
City were confident that he could take part in Pep Guardiola's team's first fixture after the international break, against Stoke, but Argentina's team doctor Donato Villani quashed all hope.
'Aguero is in a very bad mood because he was very eager to come and play and this incident, which had nothing to do with him, leaves him out of the two games', Dr Villani told TV channel TyC Sports.
Argentina face Peru and Ecuador in the final World Cup qualifiers, but the South Americans will be without the striker.
'He will be off the pitch for six weeks. He can't move in his house, or get into or out of the car', Dr Donato Villani said after speaking to Aguero.