ISTANBUL, Reuters Airbus is closing towards a potentially record deal to sell 500 narrowbody A320family jets to India39;s largest carrier IndiGo, industry sources said on Sunday.

The European planemaker has emerged as frontrunner for an order eclipsing Air India39;s historic provisional purchase of 470 jets in February, the sources said on the sidelines of an airline industry meeting in Istanbul.

Such a deal would be worth some 50 billion at the most recently published Airbus list prices, but would typically be worth less than half this after widespread airline industry discounts for bulk deals, according to aircraft analysts.

Airbus and Boeing are also still competing in separate talks to sell 25 A330neo or Boeing 787 widebody jets to the same airline, the industry sources said.

IndiGo Chief Executive Pieter Elbers, attending the annual meeting of the International Air Transport Association in Istanbul, declined to comment on commercial matters.

Airbus and Boeing also declined to comment.

Reuters first reported in March that IndiGo, which has a 56 share of the domestic Indian market, was in talks with both Airbus and Boeing for the order, which if confirmed would be the largest by a single airline ranked by the number of units.

IndiGo is already one of Airbus39;s largest customers and has so far ordered a total of 830 Airbus A320family jets of which nearly 500 are still to be delivered.

Airbus and Boeing have been racking up billions of dollars of new orders…