Leading marine scientists warned the Australian government on Wednesday of the growing threat to the Great Barrier Reef from unchecked industrial development.

More than 150 scientists from 33 institutions signed a statement saying that the mining and gas boom along the Queensland state coast was hastening the decline of the World Heritage area.

The UN's educational, scientific and cultural body meets later this month to discuss proposals to list the giant reef as a site "in danger".

A UNESCO report in March found 43 development proposals in the vicinity of the huge reef were under assessment and that the federal and state governments had failed to improve water quality in the area.

In the declaration, the scientists voiced concern about "the additional pressures that will be exerted by expansion of coastal ports and industrial development accompanied by a projected near-doubling in shipping, major coastal reclamation works, large-scale seabed dredging and dredge spoil disposal all either immediately adjacent to, or within the Great Barrier Reef World Heritage Area".

"We are calling on the Queensland and Australian governments to ensure that the outstanding universal value ... of the ... World Heritage property is protected."

Ecologist Hugh Possingham said that over the last 27 years half of the reef's coral has been degraded.

"This is just going to accelerate that, so we should really be doing the reverse," he told state broadcaster ABC.

"This just feels like a further insult, particularly the dredge and the sediments that are going to be dug up in making these ports."

Such development was "likely to be the straw that breaks the camel's back," he added.

Other signatories of the statement include scientists from the University of Hawaii, Australia's James Cook University, University of Melbourne and the Commonwealth Scientific and Industrial Research Organisation.

Ports on the Barrier Reef coast currently export 156 million tonnes of coal per annum (mtpa) and there are plans to expand that to 953 mtpa within the next decade. By 2020 an estimated 7,000 ships will traverse the reef every year, up from 5,000 in 2010.