At least 6,000 passengers were stranded Friday morning at the airport in Dalian, a major port city in northeast China's Liaoning Province, as heavy fog lasted into a third day.

Heavy fog hit Dalian, a major port city in northeast China's Liaoning Province. [Xinhua]

The local weather bureau issued an orange alarm for heavy fog early Friday, the third consecutive foggy day in Dalian.

Airport authorities said the fog, which will last until after 10 a.m., will seriously disrupt air traffic.

The Zhoushuizi International Airport of Dalian expects an estimated 45,000 passengers Friday, but nearly all the early morning flights have been postponed.

An airport spokesman said the pressure was higher as many passengers who were laid over on Thursday were still on the waiting list.

More than 140 flights were disrupted by fog Thursday. All 23 flights of China Southern Airlines were canceled.