Activity at Shanghai's international airport ground to a halt yesterday afternoon as authorities imposed extra traffic controls amid rumours of military exercises, but officials declined to give a reason for the disruption. The move delayed most planes landing and taking off, and caused some arriving flights to be diverted to Hangzhou and Nanjing , according to the airport. A Shanghai Pudong International Airport spokeswoman said: 'Higher-level departments asked us to implement air traffic controls, but they are partial. Some flights are still landing and taking off.' Operations had not returned to normal by late yesterday afternoon. It was not clear how many flights were affected, but the airport normally handles hundreds of takeoffs and landings daily. A city government spokeswoman confirmed the extra measures but said she had no knowledge of military exercises. One local journalist said domestic media organisations had been informed of military drills affecting both the Pudong and Hongqiao airports, and ordered not to report the news by propaganda authorities. Hongqiao is Shanghai's domestic airport. Japan's Kyodo news agency reported that two Shanghai-bound flights operated by Japan Airlines, one carrying cargo and the other 289 passengers, were forced to turn back because of military exercises.