Aerial photo of Great barrier reef showing reef area with some blue water and slightly cloudy sky in background.

SYDNEY, June 2 (Reuters) - Australia's iconic Great Barrier Reef is under imminent threat from industrial development and may be considered for listing as a world heritage site “"in danger" within the next year, a U.N. report said this week.

Citing the findings of a mission to the world's largest living structure in March, the United Nations Educational, Cultural and Scientific Organization (UNESCO) recommended that "“in the absence of substantial progress", its World Heritage Committee would consider such a listing in February next year.

Key pressures on the reef include coastal development, ports and liquefied natural gas facilities, extreme weather, grounding of ships and poor water quality, UNESCO said.

The reef's outstanding universal value "“is threatened and decisive action is required to secure its long-term conservation", it said.

Australian organisations managing the reef have adopted high-quality practices, UNESCO said, but noted that "“despite management successes there has been a continuing decline in the quality of some parts" of the reef.

Australia's northeastern state of Queensland, where the reef is located, is one of the country's fastest-developing regions.

Onshore are economically important coal mining operations, while the reef itself is a major tourist draw.

In recent years, critics have pointed to the dangers posed to the reef by industrial development, particularly since 2010 when a Chinese coal carrier rammed into part of the reef.

In its report, UNESCO specifically mentioned plans for liquefied natural gas facilities at Curtis Island, and ongoing development of the key coal port of Gladstone.

Future port infrastructure plans should be limited to "“existing and long-established" ports in the region, it said.

UNESCO called for the setting of clear, legal targets for the reef's condition, and said the high level of approvals for planned development in recent years was a concern.

"“Considering the high rate of approvals over the past 12 years, this unprecedented scale of development affecting or potentially affecting the property poses serious concerns over its long-term conservation," it said.

The politically influential Greens, who support Prime Minister Julia Gillard's minority government, responded to the report by calling for Australia to reduce its dependence on coal.

Australian Environment Minister Tony Burke acknowledged that climate change and coastal development posed ongoing threats to the reef, but said the report contained no surprises.

"“The UNESCO mission in March acknowledged that our management of the Great Barrier Reef World Heritage Area is still considered to be best practice," Burke said in a statement.

The World Heritage Committee will discuss the report when it meets in St Petersburg later this month. (Reporting by Chris McCall; Editing by Daniel Magnowski)