LANGKAWI, Malaysia  - Qatar Airways said it may convert its 10 orders for the Boeing Co ultra-long-range 777-8 widebody jet to the larger 777-9, depending on the performance of the 777-9.

"If the 9 is performing very close to the parameters that the 8 will operate, yes we may convert the 8 to 9," Qatar Airways CEO Akbar al-Baker told Reuters on the sidelines of an event to launch a new route from Doha to Langkawi.

Emirates and Qatar Airways are the only firm customers for the 777-8 model, which Boeing is also trying to sell to Australia's Qantas Airways Ltd for record-long commercial flights from Sydney to London.

The date of entry into service for the 777-8 will depend partly on customer demand, a Boeing executive said on Wednesday, after the U.S. manufacturer in August said plans for first deliveries in 2022 would be delayed.

The 777-9 is due to make its first test flight in 2020.

Qatar Airways also has 50 777-9s on order and will maintain 60 orders for the 777X family in total even if it converts some to the larger model, al-Baker said.

Emirates has 35 of the 777-8 model on order but its president, Tim Clark, has said some of its 150 orders for 777X family planes could be switched to 787s. 

(Reporting by Liz Lee; Writing by Jamie Freed; Editing by Shri Navaratnam and Edwina Gibbs) ((Jamie.Freed@thomsonreuters.com; +65 6318 4789;))