Aircraft manufacturer Boeing said it has received a $1.3bn order for its 737 jets from Chinese regional carrier Okay Airways, adding the airline could submit an order for larger planes later this year as part of its expansion strategy.

In a statement released at the Singapore Airshow on 17 February, Boeing said Okay Airways has reached a deal to purchase 12 single-aisle 737 planes, which include eight 737Max 8, three 737 MAX 9 and one 737 NG900 ER and has the option to acquire eight more planes.

Wang Shusheng, the airline's chairman, indicated the deal met the carrier's need to expand its fleet, after Okay Airways reported a load factor – the percentage of seats filled on a single plane per flight – reached 90% in 2015.

Shusheng added the Beijing-based airline was yet to decide whether its planned route to Hawaii and Fiji would be served by Boeing's 787 or Airbus' A350, indicating he expected the carrier to make a decision by the end of the year.

Only 5% of the airline's flights currently serve destinations outside China – with flights to Thailand, Japan and Korea – and the company revealed plans to increase the percentage to 34% over the next six years.

News of Okay Airways' order comes amid speculation that the era of bumper orders from Southeast Asia and India is reaching its end, as airlines in the region could have to put expansion plans on hold as they deal with the current growth slowdown.

Boeing, however, still expects China to overtake the US as the world's biggest aviation market over the next two decades, indicating China Eastern Airlines, Air China and other Chinese airlines will require approximately 6,330 new planes worth $950bn over the next 20 years, a figure which would represent 17% of the global demand.

In December, the US company received a $10bn order for 110 aircraft from Chinese flagship carrier China Southern Airlines.