Crew members holding a Chinese national flag pose for pictures in front of a plane of the China Southern Airlines as the plane landed at a new airport China built on Mischief Reef of the Spratlys, South China Sea, July 13, 2016. Picture taken July 13, 2016. REUTERS/Stringer

SINGAPORE (Reuters) - China Southern Airlines 600029.SS1055.HKZNH.N, the country's largest carrier by fleet size, has signed an agreement with Boeing BA.N to buy a dozen B787-9 jets worth $3.3 billion in the latest sign of booming Chinese demand for air travel.

Each of the 12 mid-size jets comes at a catalogue price of $271 million, the Guangzhou-based airline said on Wednesday, adding that the aircraft will be delivered in stages from 2018 to 2020.

“The acquisition will strengthen the construction of Guangzhou hub, thus maximizing the operational efficiency and enhancing the competitiveness of the group,” China Southern said in a filing to the Hong Kong stock exchange.

China is the world’s fastest-growing aviation market, having expanded rapidly as rising incomes resulting from years of healthy economic growth have boosted demand for internal flights as well as travel abroad for business and leisure.

China Southern's deal follows similar fleet expansion moves by rivals such as Air China 601111.SS0753.HK and China Eastern Airlines 600115.SS0670.HKCEA.N.