Heavy fog is predicted to appear again in the Three Gorges areas after two halts of navigation near the ship lock, official said on late Wednesday.

Yellow Alert has been sent as new foggy weather may cause incidents, said an official of Yichang Bureau of Changjiang Maritime Safety Administration.

The alerted areas stretches 145 kilometers upriver and 499.3 kilometers in the middle reaches of the Yangtze River, the officials said.

Continuous rainfall since Saturday is expected to last till Thursday, according to the weather forecast released on Sunday. Time to withdraw the alert could not be decided, the official said.

Heavy fog engulfed the areas twice on last Wednesday and Saturday, with over 100 and 500 passengers stranded respectively.

Due to foggy weather, navigation at the Three Gorges ship lock resumed in both directions at around midday Monday after a 37-hour halt, the longest halt since its first navigation in 2003.