BEIJING, March 26 -- China remains under pressure to contain pollution in its offshore areas, although water quality of 95 percent of the country's territorial waters met standards in 2013, a report said on Wednesday.

According to the report issued by the State Oceanic Administration (SOA), the quality of 44,000 square kilometers of sea waters was rated below Level IV -- the lowest level -- in China's offshore areas.

Inorganic nitrogen, active phosphate and fossil oil were the main pollutants, it said.

The report said that the quality of 88 percent of waters surrounding China's 431 near-shore pollutant discharge outlets failed to meet standards.

In addition, the report said 16.72 million tonnes of pollutants in the sea were from 72 rivers monitored by the SOA, a slight decrease from last year.

Around 77 percent of maritime eco-systems at estuaries and bays monitored by the administration were rated as "sub-healthy and unhealthy", it said.

The report said an oil spill last year after a pipeline blast in Qingdao City of east China's Shandong Province posed considerable threat to the maritime environment in neighboring areas.

Radioactive materials discharged into the Pacific Ocean from the crippled Fukushima power plant in Japan also affected the water environment and sea life.