The giant order, which is split mainly with rival Boeing, is for a total of 425 single-aisle aircraft, including 235 from the Airbus A320neo family, the sources said on condition of anonymity.
Last month, Reuters reported that Air India's order also involved 190 Boeing 737 MAX jets.
The order is also expected to include up to 70 wide-body aircraft, including 40 Airbus A350s, as well as 20 Boeing 787s and 10 Boeing 777Xs, the sources said.
Airbus declined to comment. Air India and Boeing did not respond to requests for comment. (Reporting by Aditi Shah, Tim Hepher ; French version by Jean Rosset ; edited by Blandine Hénault)