The Morrison government will promise another $1 billion to help save the ailing Great Barrier Reef which is still at risk of being listed “in danger” by UNESCO.

Describing the natural wonder as “the best-managed reef in the world”, the prime minister said the investment was about “backing the health of the reef” as well as 64,000 jobs linked to the reef economy, including tourism.

The latest funding promise comes on top of $2 billion previously given to agencies including the marine park authority and the Australian Institute of Marine Science and is the largest-ever investment in the reef.

Australia successfully lobbied last year to delay a decision by UNESCO about immediately listing the World Heritage protected site as “in danger” until 2023.

UNESCO diplomats were taken on a diving trip as part of the bid to convince countries to vote against an earlier draft recommendation supporting the listing.

The international agency was tasked with ongoing monitoring of the reef’s condition, but is yet to return for a visit, and the Australian government is due to submit a report by next month on how it’s protecting the reef.

The Great Barrier Reef is the world’s most extensive coral reef ecosystem with some 400 types of coral, 1,500 species of fish and 4,000 types of mollusc.

The spectacular and ancient underwater environment includes some 2,500 individual reefs and more than 900 islands and provides some of the most wondrous maritime scenery in the world.

More than half of the latest $1 billion ($579.9 million) will go towards land-based efforts to reduce erosion and run-off into the ocean from pesticides and nutrients.

A further $252.9 million will support the Great Barrier Reef Marine Park Authority’s efforts to reduce threats from the crown-of-thorns starfish and prevent illegal fishing.

As well, $92.7 million is slated for research to make the reef more resilient and to boost adaptation strategies.

The quest to save the reef includes removing the crown-of-thorns starfish. Photo: Getty

“We are backing the health of the reef and the economic future of tourism operators, hospitality providers and Queensland communities that are at the heart of the reef economy,” Prime Minister Scott Morrison said.

“This is already the best-­managed reef in the world and today we take our commitment to a new level.

“Funding will support scientists, farmers and traditional owners, backing in very latest marine science while building ­resilience and reducing threats from pollution in our oceans and predators such as the crown of thorns starfish.”

Traditional owners and community groups will get $74.4 million for a range of projects dealing with species protection, habitat restoration, citizen science and marine debris.

Reef tourism is a $6.4 billion economy. Photo: Getty

Environment minister Sussan Ley said it was a record investment.

“From breakthrough science in coral seeding and restoration, to improved water quality, the latest on water management and compliance systems, as well as the protection of native species, we are working across every aspect of the reef,” Ms Ley said.

“Our farmers, tourism operators, and fishers are our reef champions and we are supporting them through practical water and land based strategies that will contribute significantly to the health of the reef.”

-with AAP