UNESCO on Saturday urged decisive action from Australia to protect the Great Barrier Reef from a gas and mining boom, warning it risked being put on its list of world heritage sites deemed "in danger".
Australia is riding an unprecedented wave of resources investment due to booming demand from Asia, with projects worth Aus$450 billion (US$435 billion) in the pipeline.
The world's largest coral reef is not yet at sufficient risk to be declared in danger but UNESCO said the sheer number and scale of proposals including liquefied natural gas (LNG), tourism and mining projects could threaten it.
Declining water quality and climate change were the major threats and it was "essential to reduce development and other pressures as much as possible to enable an increase in the reef's resilience", UNESCO's World Heritage Committee said.
The committee said it would recommend the reef be put on the "in danger" list if some of the biggest projects went ahead.
A UNESCO mission that toured the reef in March to assess the impacts of an LNG project on Curtis Island said it had found an "unprecedented" development boom in the region with serious conservation risks.
"The outstanding universal value of the property is threatened and decisive action is required to secure its long-term conservation," the committee warned.
"The rapid increase of coastal developments, including ports infrastructure is of significant concern."
Gladstone Harbour -- a coal export hub with huge shipments to Japan, India, South Korea and China -- is undergoing a major expansion requiring dredging works which activists say is harming marine life.
UNESCO said environmental conditions stipulated by the government at Gladstone and Curtis Island, a mammoth LNG project targeting annual production of 12 million tonnes, were not tough enough to protect the reef.
It urged a "highly precautionary" approach toward new coastal and port development in the reef zone until a conservation plan had been mapped.
"Such an approach implies that (Australia) should not permit any new port development or associated infrastructure outside of the existing and long-established major port areas within and adjoining the property," UNESCO said.
Explore further: NOAA team discovers two vessels from WWII convoy battle off North Carolina