Australia is home to some of the most pristine environment on Earth, but two of its most high-profile protected areas face threats to their status as World Heritage Sites at a UNESCO meeting starting Sunday in Doha.

In such a vast country that boasts large tracts of desert, rainforest and coast, many of Australia's natural wonders have won UNESCO World Heritage listings.

They include Fraser Island, Shark Bay, the Wet Tropics of Queensland, the Greater Blue Mountains, Kakadu National Park and Uluru.

Perhaps its best-known masterpiece is the Great Barrier Reef, one of the most biodiverse places on the planet that sprawls across an area roughly the size of Japan.

But all is not well on the reef, which is considered to be in "poor" health.

It is under growing pressure not just from climate change and the destructive coral-eating crown-of-thorns starfish, but agricultural runoff and rampant coastal development linked to mining.

For these reasons, UNESCO is considering downgrading its status to "World Heritage in Danger" at its annual meeting, in the absence of Australia showing "substantial" progress in dealing with the problems.

Environment Minister Greg Hunt insists Australia has thrown millions of dollars at protecting the reef, bolstering its resilience to the major threats of extreme weather events and climate change.

Working to reduce outbreaks of the crown-of-thorns starfish was also being tackled, as was reducing nutrient and sediment run-off from land-clearing and agriculture, he said.

Queensland state Environment Minister Andrew Powell, who released a report Thursday on water quality that he will take to the Doha meeting, said he was confident a downgrade would be avoided.

"The reef is now on the pathway to long-term improvement," he said, pointing to improved land management practices that had reduced pesticide loads by 28 percent since 2009.

"In terms of nitrogen -- that's what causes those crown-of-thorn starfish outbreaks -- we've reduced it by 16 percent overall," he added.

- Reef a 'dumping ground' -

While improvements to water quality had been achieved, Powell conceded that the overall health of the reef still needed more work.

The report did not deal with port developments linked to mining, which conservationists have warned could hasten the demise of the reef.

There has been particular concern from UNESCO about the approval in December of a massive coal port expansion in the region, and allowing the dumping of millions of tonnes of dredge waste within the marine park waters.

The Australian Marine Conservation Society said while a reduction in sediment from farming was good news, dredging was ruining the reef.

"The mining industry, backed by the state government and the state-owned ports corporations, are treating the reef as a dumping ground," said spokeswoman Felicity Wishart.

- Abbott's 'environmentally reckless' move -

Another of Australia's natural wonders under threat is the Tasmanian Wilderness, one of the last expanses of temperate wilderness in the world that covers nearly 20 percent, or 1.4 million hectares, of the southern island state.

Prime Minister Tony Abbott believes too much forest is locked up, and favours more access for loggers.

He has requested UNESCO remove its World Heritage status for 74,000 hectares of the area, claiming it was not pristine -- the first time a developed country has asked for a delisting.

The move has been labelled "environmentally reckless" by green groups.

"Logging World Heritage forests is as reckless as destroying any other World Heritage site, like using the Grand Canyon as a garbage dump, knocking down the Sydney Opera House for harbourside apartments or selling the Eiffel Tower for scrap," said Wilderness Society spokesman Vica Bayley said.

"If Tasmania's World Heritage forests aren't safe, neither are our other iconic World Heritage sites, such as the Great Barrier Reef, the Daintree rainforest, Kakadu and the Blue Mountains."