Australian Research Council Centre of Excellence for Coral Reef Studies and South China Sea Institute of Oceanology researchers blamed China's economic boom for the shrinkage by at least 80 per cent of coral reefs in the region over the past three decades.

The decline hit coastal fringing reefs along the Chinese mainland and the nearby Hainan Island, said the study which was published in the latest edition of the Conservation Biology journal.

"On offshore atolls and archipelagos claimed by six countries in the South China Sea, coral cover has declined from an average of greater than 60 per cent to around 20 per cent within the past 10-25 years," the report said.

Other studies have shown that large parts of China are environmentally damaged by severe air, water and land pollution, sparking protests and leading to the scrapping or postponement of planned new factories.

The study said coral loss was worsened with poor governance due to the competing claims among China, Brunei, Malaysia, the Philippines and Vietnam. The reefs in the area stretch 30,000 square kilometers.

Study author Terry Hughes said that some marine parks that aim for conservation established in the region were too small and too far apart to make a difference in averting the decline in coral cover.

"The window of opportunity to recover the reefs of the South China Sea is closing rapidly, given the state of degradation revealed in this study," AFP quoted Mr Hughes.