Lion Air, Indonesia’s largest privately owned carrier and one of the world’s largest Boeing 737-900ER customers, has issued a request for proposals for additional narrowbody aircraft, according to industry sources. The size of the potential Lion Air order is unclear, but one industry executive says the number is 200 aircraft. Lion Air’s founder and president director, Rusdi Kirana, was unavailable for comment.

The competition is between the Boeing 737NG/737 MAX and the Airbus A320/A320NEO, say industry executives. Airbus has made a very competitive bid in an effort to win market share and woo Lion away from Boeing, say some of the executives. If this is true, it could pressure Boeing to match Airbus’s offer.

Lion Air traditionally has been a staunch Boeing supporter. The Aviation Week Intelligence Network (AWIN) database shows Lion Air operates 53 737-900ERs and has another 115 on order.

In a separate development, Lion Air is establishing an aircraft leasing company in Singapore. Part of the company’s role will be to lease aircraft to the new joint-venture airlines Lion Air plans to start in Asia, say industry executives. The carrier already is working to establish an airline in Malaysia in partnership with Malaysian company Berjaya Group. The group’s airline, Berjaya Air, will be used as the vehicle for the new joint venture. The JV intends to transform Berjaya Air, a small turboprop operator, into a low-cost carrier operating 737-900ERs and ATR 72-500s.