Budget carrier IndiGo firmed up a record order for 180 single-aisle Airbus aircraft at the Paris Air Show on Wednesday.

The order includes 150 of Airbus' revamped A320neo aircraft and 30 of its existing A320s, and it follows a memorandum of understanding signed in January, Airbus said. The deal is worth $16.2 billion at list prices.

Engine selection will be announced by the airline at a later date, Airbus said.