ZHENGZHOU - Traffic resumed on China's most bustling railway line linking Beijing with southern Guangzhou city nearly five hours after a passenger train on the stretch of track lost power in Zhengzhou, capital of central Henan province, Wednesday morning.

The Zhengzhou Bureau of Railways said the train, numbered D615, on its way from Beijing to Wuhan city, lost power at about 7 am and was replaced by a backup train by noon.

The accident has also delayed at least five other train trips on the artery rail line.

The city of Zhengzhou was enveloped in a dense fog Wednesday morning, which reduced the visibility to less than 500 meters, according to the city's observatory.

The railway authority said that the train's glitches are related to the foggy weather.

The fog also affected many other regions of China, which is now in the Spring Festival rush.

In Beijing, fog started to linger from Tuesday night, adding pressure to the road traffic. The municipal weather department has issued a warning, forecasting the conditions will last for all of Wednesday.

In northwest China's Xi'an, capital of Shaanxi province, over 6,000 passengers were stranded at the airport on Wednesday morning as the fog reduced visibility to less than 100 meters and caused the delay of 74 flights. Another 70 flights destined for Xi'an were diverted to other airports nearby.