QINGDAO, Sept. 22 -- Chinese scientists have discovered two sites of gas hydrates, or combustible ice, which are exposed on the sea floor in the South China Sea.

The Chinese Academy of Sciences institute of oceanology said on Friday that the discoveries were made during a month-long expedition in the western Pacific Ocean undertaken by the research vessel Kexue.

The two sites are at about a depth of 1,100 meters. It is the first time exposed combustible ice has been discovered in sea areas under the jurisdiction of China, according to the institute.

Combustible ice usually exists in deep sea sediment or tundra areas which have high pressure and low temperature necessary for its stability. It is rare to see the substance exposed on sea floor.

China declared its first success in collecting samples of combustible ice in the South China Sea on May 18 after discovering the substance there in 2007.

Combustible ice can be ignited like solid ethanol. One cubic meter is equal to 164 cubic meters of regular natural gas.