PARIS –  Airbus says Indian budget airline IndiGo has finalized an exceptionally large order for 250 single-aisle A320neo jets.

IndiGo, India’s largest domestic airline, had signed a preliminary order last year and firmed it up Monday, Airbus said in a statement. Airbus called it the company’s biggest ever order by number of jets.

At list prices, the jets would cost $26 billion, though customers usually negotiate discounts.

Several Asian low-cost carriers are building up fleets amid growing demand. IndiGo’s president Aditya Ghosh said the order would allow his company to further develop low-cost travel in India and abroad.

The A320neo is an upgraded, more fuel-efficient version of Airbus’ popular A320 jets, usually used on mid-range flights.