Airspace controls that were imposed over eastern China starting on Nov. 20 might be extended until Nov. 25, sources with China Eastern Airlines said on Nov. 22.

The controls, imposed for unspecified reasons, have affected thousands of passengers traveling to and from eastern China, particularly at airports in Shanghai and Guangzhou.

Sources at the Baiyuan airport in Guangzhou, where flights were delayed for at least 1,600 passengers on Nov. 20, said several flights were still affected on Nov. 22, but only for brief periods, with no large-scale passenger delays.

The airport advised passengers to follow updated flight schedules through phone calls, text messages or logging onto the airport website.

Shanghai's two airports did not give information on the exact number of flights postponed on Nov. 22. Arrival information on their websites indicated that at least 20 flights were delayed, but it is not known whether the delays were all caused by the airspace controls.

As of Nov. 21, the aviation ban had delayed about 150 flights from Shanghai's two airports bound for Guangzhou, Xiamen, Shenzhen, Beijing and Dalian, and affected more than 7,000 passengers.