A new flight route, M503, was put into operation on Sunday over airspace in China's southeastern region.

Flight 857 of Hong Kong-based airlines Dragonair was the first plane to ply the route on its Pudong (Shanghai)-Hong Kong flight.

On Sunday, 33 passenger planes are expected to fly the new path, according to the mainland's civil aviation authorities.

M503 is one of several routes that will take planes over the Taiwan Strait from Zhejiang Province and the cities of Fuzhou and Xiamen in Fujian Province.

The route is designed to ease air traffic congestion amid increased flights over the Yangtze River and the Pearl River delta areas.

M503 was designed in cooperation with the United States and other countries, and approved by the International Civil Aviation Organization.

The route was set within the Shanghai Flight Information Region instead of the Taipei region, and it maintains a safe distance from the Taipei region.