IAG shocked the industry nearly three years ago when it placed a tentative order for 200 Boeing 737 MAX jets at the Paris Airshow in 2019, at a time when the aircraft was grounded worldwide after two fatal crashes.
The deal was perceived as a show of confidence in troubled Boeing by IAG boss Willie Walsh.
The sources said Boeing looked likely to keep a slimmed-down version of the order, potentially involving closer to 50 jets than the original blockbuster quantity of 200.
If a deal is confirmed in ongoing negotiations, Boeing's MAX is seen most likely to be deployed at Vueling and future low-cost operations at London Gatwick.
IAG also has options to order additional narrowbody aircraft from Boeing's European rival Airbus, inherited from earlier purchases. Further Airbus orders may also depend on progress in negotiations over undelivered A350 aircraft, the sources said.
International Airlines Group is the parent company of British Airways, Aer Lingus, Iberia, Iberia Express, Vueling, LEVEL, IAG Cargo, and Avios Group.
