Heavy fog was to blame for cancellations and delays to high-speed trains and flights in much of the country on Wednesday.

Fog shrouded nine provinces and municipalities in North, East and South China with two high-speed trains being canceled and many others delayed, the railway authorities confirmed.

The fog caught many passengers on the high-speed services unprepared.

"It's sad to look out of the window and see the ordinary trains traveling smoothly while the high-speed trains are stranded," Ren Li, a Beijing resident who was stranded on a train, said on her micro blog. Ren's train was delayed for an hour and 20 minutes.

In Shanghai, 298 flights have been canceled and 440 flights delayed at Pudong International Airport since dense fog enveloped the city on Monday morning.

Zhao Yongbo, a publicity officer with Jilin provincial government, said his flight from Changchun to Shanghai was canceled and he had to fly to nearby Hangzhou and then drive to Shanghai to attend a conference.

Flights at other airports, such as Lukou airport in Nanjing, Jiangsu province, and Meilan airport in Haikou, Hainan province, were also delayed or canceled.

Meanwhile, meteorological authorities in Beijing and Shanghai say that lingering fog in North and East China should dissipate with the arrival of a cold air front bringing rain.

Sun Jisong, chief forecaster of the Beijing meteorological bureau, said the foggy weather "will clear up for most provinces and municipalities in North China on Wednesday night and Thursday".

Yan Yan, assistant to chief meteorological officer in Shanghai meteorological bureau, also said the fog will clear on Thursday when cold air arrives.