About 25 percent of China's coastal areas are moderately or heavily polluted, according to a new report on the country's oceanic environment released on Friday.

Related readings: Tehran pollution kills 3,600 in a month Ambitious "blue sky" target for Beijing Officials under criticism for fabricating pollution figures Pollution to be cut for Games Newcomers have a nose for job Pollution turning seabeds into desert: report 38b tons of waste water flows into major rivers

The report revealed that 149,000 square kilometers of the total sea area in 2006 did not meet the national standard for "clean" water, 10,000 square kilometers more than the previous year.

Fifty-five percent of the water in China's 110,000 square kilometers of coastal areas also failed to be classified as "clean".

The eco-systems in most bays, river mouths and coastal wetlands were described as unhealthy due to 81 percent of drains that carry waste into the sea discharging pollutants that exceed the national standards. Of the 609 drains that were monitored, only 5.6 percent were established in areas specifically designated as pollutant discharge areas.

China reported 93 cases of red tide in 2006, which increased by 13 percent over the previous year. Red tide, caused by poisonous alga, is occurring regularly and is increasingly eroding the coastline, the report said.