The delays caused by the military exercises are scheduled to last until the middle of next month.

Chartered flights and the use of executive aircraft at affected airports have been suspended to try to ease delays.

Airlines have also been urged to cut the number of scheduled flights.

International flights may not be affected because they are normally given priority at mainland airports, a duty supervisor for Air China at Shanghai Pudong International Airport told the .

Cathy Zhang, an American-Chinese woman who took a flight from Shanghai Pudong to Lanzhou yesterday, said the disruption to services was unnecessary.

"Military drills should not disrupt ordinary people's lives, right? If they think the exercises are necessary they should do them in the evenings or before the summer vacation," she said.

Another passenger who flew to Bangkok yesterday from Shanghai Pudong said her friends had told her many flights were delayed because of the military drills, but she thought the disruption was understandable.

"If our country needs this large-scale military drill we should understand and support it," she said. "Look at those small countries that are provoking us. I think more drills are justified."

Yue Gang, a military commentator and retired PLA colonel, said the civil aviation authority was becoming more open about informing the public about possible disruption from military exercises. "By informing the public in advance, the aviation authority won't receive so many complaints because people can get prepared," he said.

Between noon and 5pm yesterday, 15 flights were delayed and one cancelled at Shanghai's two airports.