Italy's industry ministry has postponed a deadline to present a rescue plan for Alitalia to October 15, with sources saying the rescuers were at odds on key aspects of the proposal for the loss-making carrier. 

Italian state-owned railway group Ferrovie dello Stato, US airline Delta and infrastructure group Atlantia have been discussing how to revive Alitalia for two months.

They had been expected to present a binding proposal by September 15. 

The delay, the sixth since Ferrovie expressed its interest in investing in the carrier, means Alitalia will remain under special administration. 

Two sources close to the matter told Reuters the Italian partners in the consortium and Delta did not see eye to eye over the development of Alitalia's routes in North America and the need to inject more money in the carrier in the long term. 

A possible management reshuffle at Atlantia could also complicate the rescue plan for a carrier that has already been through two unsuccessful rescues.