China's airspace restrictions need to be updated to give more room to civil aviation, the head of China Southern Airlines said on Monday.

Wang Changshun, who is a deputy to the National People's Congress, the top legislature, said air traffic controls and airspace restrictions "have held back development of the civil aviation industry and caused flight delays".

Some civil aviation routes now in use were planned in the 1950s and '60s and are outdated, said Wang, whose airline is the country's largest carrier in terms of fleet size.

He explained that even though the direct route between two domestic airports may be 1,000 kilometers, restrictions mean private aircraft must make detours, which can add as much as 500 km to a journey.

Fu Puyan, who runs China Southern's branch in the Xinjiang Uygur autonomous region and is also a NPC deputy, said lifting some airspace restrictions would improve connectivity between China and countries on the Silk Road Economic Belt, one of the routes that make up the Belt and Road Initiative.

"Currently, aircraft departing from southern Xinjiang's Kashgar city, a key transportation hub on the economic belt, have to fly southward before heading west to some Central Asian countries, which adds more than an hour to the flight time," he said.

Wang added that he also hopes the Ministry of Foreign Affairs will make more efforts in negotiating international air rights, so that Chinese airlines can fly more frequently to more destinations to meet the surging demand for overseas travel.