Flight 501, from Taipei to Shanghai’s Pudong International Airport, was diverted to Hangzhou, a city about 100 miles southwest of Shanghai, where it landed without incident. A search of the plane and the 297 passengers’ luggage turned up no explosives.

Shanghai is hosting a world exposition, which opened with great fanfare on Friday, with 20 state leaders in attendance.

The American man, identified only by his surname Lin, was arrested as he left the aircraft, news agency reported. He later told the authorities that he was joking, according to a report by Hangzhou cable television station TVBS.

The flight eventually left for Shanghai after a four-hour delay and landed about 5 p.m. Saturday. The Associated Press quoted a China Airlines spokesman, Bruce Chen, as saying that the passenger was traveling on an American passport and had acted “very calmly” when he told the crew that he had a bomb. He did not appear to have been drinking, Mr. Chen said.

Chinese authorities have taken extraordinary security measures to avert incidents in Shanghai as the Expo 2010 began on Friday. The government even sealed China’s borders with neighboring Kyrgyzstan and Kazakhstan, some 2,300 miles from the Expo site, on the chance that someone intent on disrupting the event might enter the country.

Chinese aviation officials had no comment on the episode, which went unreported on state-supervised media on Saturday evening.

Source: New York Times