The six-year study released Tuesday by Australian and US researchers examined 48 reefs strung 1,500 kilometres (930 miles) along the Great Barrier Reef, the world's largest living organism off Australia's east coast.

Previously, the link between ocean warming and a coral disease known as "white syndrome" had been speculative but the study found "a highly significant relationship" between the two.

"Our results suggest that climate change could be increasing the severity of disease in the ocean leading to a decline in the health of marine ecosystems and the loss of the resources and services humans derive from them," the researchers said.

Lead researcher John Bruno, of North Carolina University, said understanding the causes of coral disease could help scientists preserve vulnerable coral reefs.

"More diseases are infecting more coral species every year, leading to the global loss of reef-building corals and the decline of other important species dependent on reefs," he said.

"We've long suspected climate change is driving disease outbreaks. Our results suggest that warmer temperatures are increasing the severity of disease in the ocean."

A report last January warned the Great Barrier Reef -- a World Heritage site stretching over more than 345,000 square kilometers (133,000 sq miles) -- risks becoming "functionally extinct because of climate change".

The assessment in a draft international report by the UN Intergovernmental Panel on Climate Change (IPCC) warned coral bleaching would become more common on the reef as the ocean became warmer and more acidic.

Bleaching occurs when the plant-like organisms that make up coral die and leave behind the white limestone skeleton of the reef.