MIAMI — China Southern Airlines has finalized yesterday a $3.2 billion order with Boeing to acquire a dozen of 787-9 Dreamliners, in the latest sign of booming air travel demand in China.

The Guangzhou-based carrier said on Wednesday that the new jetliners, to be delivered between 2018 and 2020 will strengthen its expanding long-haul fleet.

“The 787 Dreamliners have helped us to achieve initial success in implementing our internationalization strategy in the past few years and enabled us to make our operation and services more appealing to passengers,” said Tan Wangeng, CEO, China Southern Airlines. “The additional new 787-9s will further increase our capacity and services for our long-haul routes.”

China is the world’s fastest-growing aviation market, having expanded rapidly as a rising middle class with a strong purchasing power has boosted demand for deomestic flights as well as international travel.

China Southern Airlines, China’s launch customer of the 787, currently operates 10 787-8s. The airplanes have enabled the Guangzhou-based carrier to launch six new non-stop global routes, connecting Guangzhou to London and Rome in Europe, Vancouver in North America, as well as Perth, Auckland and Christchurch in the Oceania area.

China’s largest airline by fleet size, China Southern Airlines currently operates 700 aircraft, including Boeing 787, 777, 747, 757 and 737s. By 2020, the airline expects to have a fleet of 1,000 aircraft with passenger traffic surpassing 160 million annually.