Fishing boats are trapped in sea ice in a port at Xikou Village in Yantai City, East China's Shandong province, Jan 26, 2016. [Photo/Xinhua]

BEIJING -- The National Marine Environmental Forecasting Center (NMEFC) of China issued a yellow alert for sea ice on Monday, the first this winter.

Acreage of sea ice in Liaodong Bay in Northeast China's Bohai Sea has risen to 79 sea miles, 70 percent of the Liaodong Bay area.

According to the center, the declining water temperature in northern sea areas caused by the cold wave in late January has contributed to the expansion of the ice, while the direction of the cold front led to more drifting ice.

The NMEFC forecast that the ice will remain stable for the next three days and called for more icebreaking in Liaodong Bay.

In addition, the center urged local administrative bodies to ensure the supply of necessities and emergency aid to island residents affected by the ice.

China has a four-tier warning system for sea ice, with red being the most serious, followed by orange, yellow and blue.