A US think tank has warned of environmental threats to the South China Sea, as some regional powers push ahead with reclamation work there amid ongoing territorial disputes.

China claims jurisdiction over most of the South China Sea, and has been building artificial islands to set up runways and other facilities. Other claimants include some Southeast Asian countries and Taiwan.

Researchers at the Center for Strategic and International Studies, or CSIS, say they have studied satellite imagery and other data from the last 10 years to analyze conditions in the South China Sea.

They say the analysis shows that China is not alone in engaging in dredging and landfill work. Vietnam, Malaysia, the Philippines, and Taiwan are also harming the sea's coral ecosystems.

The researchers say China's land reclamation projects at 19 locations cover the greatest area of the sea. They say Vietnam is developing 20 locations, Malaysia five, and the Philippines and Taiwan one each.

The researchers note that the method employed by China and Vietnam places a particularly heavy burden on the environment. It involves using a pump to quickly suck up sediment from the seabed.

They also say the process has killed nearby marine life. The rich ecosystems being harmed are home to more than 6,500 marine species.

One of the researchers, Harrison Pretat, called for an end to reclamation projects in the South China Sea.

He said the ecosystems could be so severely damaged in the coming decades that they can't be restored.

He went on to say this would affect the food security of neighboring countries and territories that depend on the sea. He called on them to put aside their disputes and address the environmental problem together.