Boeing Co will sell China 300 airplanes and build a 737 aircraft completion center in the country, Xinhua news agency announced Wednesday. The deal was reached during Chinese President Xi Jinping's current state visit to the United States.

China is Boeing's largest international market, accounting for about a quarter of Boeing deliveries so far this year. The airplanes in the latest deal are worth $38 billion at list prices. Xi, who arrived in Seattle on Tuesday aboard a Boeing 747-400 Air China plane, visited Boeing's Paine Field factory on Wednesday.

Commercial Aircraft Corp of China Ltd, also known as Comac, signed a cooperative agreement with Boeing for the center, Xinhua reported without elaborating.

"Boeing airplanes have played an important role in supporting the development of China's aviation transportation for the past 40 years," said Li Hai, president of China Aviation Supplies Holding Company. "These additional airplanes will further help connect the people in China and around the world."

The package includes 240 airplanes for Chinese airlines, including 190 737s and 50 wide-body aircraft, and another 60 737s for leasing companies ICBC and CDB Leasing.

"China is a critical international market for commercial airplanes," said Boeing Commercial Airplanes President and CEO Raymond Conner. "We thank our Chinese customers for selecting fuel-efficient Boeing airplanes to meet their fleet growth and expansion."

The 737 completion and delivery center will be the first facility of its kind outside the US for Chicago-based Boeing. European plane maker Airbus Group SE, which competes with Boeing for plane orders, already has a similar facility in Tianjin, near Beijing. Airbus signed an agreement in July to set up its second Chinese plant.

In two decades, China is expected to displace the US as the world's biggest aircraft and travel market, according to Boeing. It predicts airlines will need to add 6,330 new planes worth $950 billion by 2034 to keep pace with travel growth.

China will become the world's biggest air passenger market by 2034, with one in five passengers traveling to, from or within the country, the International Air Transport Association said in April. The number of air passengers traveling to, from and within China is set to nearly triple by 2034 to some 1.3 billion, surpassing an expected 1.2 billion for the United States, according to official estimates.