Indian budget carrier IndiGo could confirm an historic $16 billion order for 180 Airbus aircraft at the Paris Air Show on Wednesday, industry sources said.

The deal was provisionally announced in January but has been mired in further negotiations before it could be signed and go into the Airbus order book in a boost for parent EADS .

The deal is seen as the largest commercial jet order by number of aircraft but could be eclipsed by a roughly 200-plane order expected from AirAsia on Thursday.

Airbus declined to comment. Asian airlines are leading a rebound in commercial aviation demand to feed a multi-speed economic recovery marked by strong growth in emerging markets. Airbus says emerging markets will make up 70 percent of global air travel by 2030.

In January, IndiGo provisionally ordered 150 revamped A320neos, which are promising airlines fuel savings when they enter service in 2015, as well as 30 current models of the A320.

The A320 is a 150-seat plane which competes with Boeing's 737. Both have fuelled the expansion of low-cost carriers.

IndiGo is looking at an initial public offering to help finance the order.

The IndiGo deal, if confirmed, will be a further boost for engine maker Pratt & Whitney , which has been selected to power the A320neos ordered by IndiGo.