The Turnbull government will deliver the largest single environmental protection package in Australian history by committing half a billion dollars to protect the Great Barrier Reef from climate change and pollution.

The investment, to be detailed in the May budget, will aim to shore up support in key Queensland seats ahead of an election in the next year, as the Coalition tries to balance environmental concerns with its pro-mining jobs focus through the Adani coal mine.

A diver on the outer Great Barrier Reef near Port Douglas. Credit:Jason South

The significant funding boost comes days after internal government figures obtained by Fairfax Media showed that Commonwealth funding to arrest declining water quality on the reef had dropped by more than $11 million a year.

The reef – a World Heritage area and the largest living structure on the planet – has been decimated by coral bleaching and pollution, losing up to half of its coral cover in the past 30 years.