The Great Barrier Reef should be put on a list of World Heritage Sites that are "in danger" due to damage caused by climate change, Unesco says, APA reports citing BBC.
The UN's cultural body says the world's biggest coral reef system should be downgraded to the list at a meeting next month.
It has urged Australia to take "accelerated action" on global warming.
But the Australian government said it would "strongly oppose" the recommendation.
The latest row is part of an ongoing dispute between Unesco and the Australian government over the status of the iconic site.
The reef, stretching for 2,300km (1,400 miles) off Australia's north-east coast, gained World Heritage ranking in 1981 for its "enormous scientific and intrinsic importance".
After Unesco first debated its "in danger" status in 2017, Canberra committed more than A$3 billion (£1.bn; $2.2bn) to improving the reef's health.
However, several bleaching events on the reef in the past five years have caused widespread loss of coral.
Scientists say the main reason is rising sea temperatures as a result of global warming caused by the burning of fossil fuels.