Former minister Tony Burke was expected to approve an application to dredge 3 million tonnes of spoil and dump it out at sea as part of an expansion of the terminal’s capacity from 50 to 120 million tonnes per annum.

But Butler has said he will push back his decision to at least August 9 as he further investigates the dredging’s environmental impact on the Great Barrier Reef.

Butler is devising a new plan to avert the reef’s status being downgraded to a “World Heritage Site in Danger” by UNESCO.

While UNESCO will make its finding on the state of the reef next June, it has warned about potential impact of resources development on the coast.

Butler said $375 million would be spent between 2013 and 2018 to improve overall water quality.

The government’s draft Great Barrier Reef Ports Strategy is consistent with UNESCO’s recommendations that port development be constrained to existing areas, Queensland Infrastructure Minister Jeff Seeney said.

The previous Labour government had planned an expansion to 10 coal terminals. A new multi-cargo loading facility had berths for 12 ships, requiring dredging of 40 million cubic metres of the sea bed, he said.

“In contrast, our government moved quickly to take this huge and irresponsible proposal for Abbot Point off the table,” he said.

“We have put a stop to it and will approve only a balanced, incremental increase in coal shipping from Abbot Point.”