BEIJING, July 26 (Xinhua) -- China's airline regulator on Saturday issued an orange alert for massive flight delays in eastern and central China, saying the traffic capacity of some routes may drop as much as 65 percent.

"The airspace in east China will be quite busy on Saturday," the Civil Aviation Administration of China (CAAC) said in a statement, noting at least 23 airports will be affected, including those in Shanghai, Nanjing, Nanchang, Hefei, Zhengzhou and Wenzhou.

The CAAC said in an earlier statement that "rainstorms, routine military exercises and other comprehensive factors" were behind widespread flight delays and cancellations.

In Shanghai, the air traffic's busy hours will last between 8 a.m. to 12 p.m. and between 3 p.m. to 7 p.m. on Saturday, reducing air traffic capacity by 65 percent.

During the same period, the civil flight handling capacity in airspace above the Zhengzhou area will drop by 60 percent, according to CAAC.

During busy hours, flights will be unable to land at airports in the cities of Linyi, Xuzhou, Lianyungang, Huai'an, Yancheng, Changzhou, Yangzhou and Nantong, while flights departing for airports in Nanchang, Ganzhou, Jiujiang, Yichun, Jinggangshan, Jingdezhen, Wuyishan and Wenzhou will not be allowed to take off.

At least 14 flights operated by six airline companies in Shanghai were canceled as of noon on Saturday.

The CAAC is seeking to address the issue by setting up temporary air routes and allowing airlines to alter flight plans, according to the previous CAAC statement.

The CAAC also banned applications for business jet flights, additional flights and charters at the affected airports.