Australia welcomed a draft UNESCO decision not to list the Great Barrier Reef as an endangered site, its assistant tourism minister said on Saturday, despite ongoing struggles of the world's biggest coral reef ecosystem with coral bleaching.

The reef, which has suffered several mass coral bleaching events in recent years, is not currently on the United Nations Educational, Scientific and Cultural Organization (UNESCO) list of world heritage sites that are in danger, although UN scientists have previously recommended that it should be added.

Australia's government has lobbied for years to keep the reef - which contributes more than A$9.0 billion ($6.25 billion) to the economy annually - off the list, as it could damage tourism at the site, which receives more than 2 million visitors each year.

Assistant Tourism Minister Nita Green said the decision overnight by the UNESCO World Heritage Centre "recognises Australia's continued efforts to protect and manage this important icon".

"Australia welcomes UNESCO's decision to not list the reef as endangered, and recognise all of the work that's been going into protecting the reef," Green said in televised remarks from the capital Canberra.

The reef, home to 400 types of coral and 1,500 species of fish, stretches for some 2,400 km (1,500 miles) off the coast of the northern state of Queensland.

Since 2016, it has experienced five summers of mass coral bleaching, when large sections of the reef turn white due to heat stress, putting them at greater risk of death. Climate change is a primary driver of rising sea temperatures which cause coral bleaching, according to the Queensland government.

($1 = 1.4409 Australian dollars)