India's largest airline IndiGo is in early-stage discussions with Brazilian aircraft manufacturer Embraer to buy 100 regional jets, with an option for about 50 more, according to three people with direct knowledge of the matter. The potential order would be among the largest placed with Embraer, although no agreement has been reached and the transaction is not guaranteed. The aircraft model has not been finalised, and the size of the order could change as negotiations progress. Any deliveries would begin in 2030 at the earliest, according to two of the people. IndiGo and Embraer had not responded to requests for comment at the time of publication. The number of aircraft under discussion had not previously been reported. A purchase of 100 jets would strengthen Embraer's position in India, the world's third-largest domestic aviation market, where airlines are expanding their fleets to meet long-term demand for air travel. Embraer has been promoting its regional aircraft to Indian carriers and signed a non-binding pact this year with Adani Defence & Aerospace to examine a final assembly line in India for its older-generation E175-E1 jets, which can seat up to 88 passengers. Embraer also produces the larger E190-E2 and E195-E2 aircraft, which have newer, more fuel-efficient engines and can accommodate up to 114 and 146 passengers respectively. Star Air, a small regional carrier, is currently the only Indian airline operating Embraer aircraft. Embraer Chief Executive Francisco Gomes Neto said in March that the proposed India assembly line depended on orders for at least 200 aircraft, with India-assembled jets potentially available from 2028 if orders were secured by the end of this year. For IndiGo, an Embraer order could support additional routes to regional areas and help replace some of its ATR turboprops, allowing it to offer more seats on existing services. Chief Executive Willie Walsh, who took charge in August, has outlined plans to expand long-haul flying while protecting the airline's low-cost short-haul business. IndiGo aims to grow its fleet to around 600 aircraft by 2030, from 442 in September; its fleet is largely made up of Airbus narrowbody jets and includes 44 ATR turboprops.