Boeing Dreamliner 787 Air China planes sit on the production line at the company's final assembly facility in North Charleston, South Carolina.

Boeing on Tuesday raised its forecast for China's aircraft demand for the next 20 years, underpinned by expectations of robust air travel demand, but growth in new fleet will be slower than the plane maker's prediction last year.

Chinese carriers will need 8,090 new planes through 2038, 5.2% higher than Boeing's forecast last year. That would be

worth nearly $1.3 trillion based on list prices.

Last year, Boeing forecast a 6.2% growth in the country's new aircraft demand to 7,690 planes for the period to 2037.

"An expanding middle class, significant investment in infrastructure, and advanced technologies that make airplanes more capable and efficient, continue to drive tremendous demand for air travel," said Randy Tinseth, vice president of commercial marketing for Boeing.

Boeing and its European rival, Airbus, have been jostling to increase market share in China, the world's fastest growing aviation market, with both opening assembly plants in the country.

But the global grounding of Boeing's 737 MAX fleet in the wake of two fatal crashes have constrained the ability of

Chinese airlines to expand capacity, with softer travel demand pressuring passenger yields amid a slowing economy.

Boeing projected a need for 5,960 new single-aisle airplanes over the next 20 years, representing 74% of total new

deliveries, while China's wide body fleet will require 1,780 new planes, tripling the country's current wide body fleet size.

China will also need about $1.6 trillion worth of commercial services for its aircraft fleet over the period, Boeing said.