Revealed: The mystery buyer of $20 billion worth of planes

The Boeing 777X is scheduled to enter service in 2020.

Singapore Airlines has been revealed as the buyer of new-generation Boeing widebody planes worth US$13.8 billion ($19.82b).

The order, previously attributed to an unidentified customer, is for 20 777-9s, an aircraft that is still being developed, and 19 stretched Dreamliners, the 787-10s that is due to enter service with airlines next year.

The airline will have got a discount to the list price released, but Boeing says the value of the transaction would sustain thousands of United States suppliers and more than 70,000 direct and indirect US jobs. The airline also has options for 12 more planes: six of each type.

Singapore Airlines flies to Auckland, Wellington and Christchurch and the new planes would be suited to the routes.

The signing ceremony, witnessed by US President Donald Trump and Prime Minister of Singapore Lee Hsien Loong, included Singapore Airlines' CEO Goh Choon Phong.

"These new aircraft will also provide the SIA Group with new growth opportunities, allowing us to expand our network and offer even more travel options for our customers," said Goh.

Singapore Airlines has more than 50 Boeing 777s in service and is the launch customer of the 787-10, which is set to be delivered in the first half of next year.

With an existing order for 30 787-10s, the airline now has 49 on order, making it the largest customer for this type.

A long-range airplane that's efficient at any stage length, the 787-10 will serve the airline's medium-range operations while partnering with the 777-9 for the carrier's long-haul routes.

More than 600 Dreamliners have been delivered to 60 airlines of a total of 1280 orders.

Since entering service in 2011 after bumpy development and early manufacturing, the aircraft have flown 200 million people on more than 560 unique routes.

The 787-10, the largest family member, adds seats and cargo capacity and will be able to connect all points within Asia at lower seat costs than any other twin-aisle airplane, with the flexibility to also link to Europe, Africa and Oceania.

The new model 777 will draw on technology from the Dreamliner and will have carbon fibre wings that fold at their tips to allow them to fit into more airports.