Fishing boats are seen trapped by sea ice in Laizhou Bay, east China's Shandong Province, Jan. 12, 2010. The most severe icing situation in the past 30 years in the coast off Shandong Province continued to worsen amid cold snaps. Sea ice appeared last week along the coastline of the Bohai Sea and northern Yellow Sea as cold fronts pushed the temperature down to minus 10 degrees Celsius.[Xinhua]

China's National Marine Forecasting Station on Tuesday issued an alarm on sea ice as it was developing fast off the country's eastern coast.

In the following week, the floating chunks of ice could extend up to 90 nautical miles off the coast of Bohai Sea and 25 nautical miles in the northern Yellow Sea. The ice thickness could measure up to 40 cm, the station said.

The station warned of threats to port infrastructure, transportation and maritime operations.

The worst sea ice in the past 30 years appeared from early Jan. along the coastline of the Bohai Sea and northern Yellow Sea as cold fronts pushed the temperature down to minus 10 degrees Celsius and below.

Sea ice in the Liaodong Bay nearly doubled to 71 nautical miles Tuesday from 38 nautical miles on December 31.

With another cold front expected this week, the sea ice along the coastline would further develop, the station said.