The Federal Government has again delayed its decision on approval for the planned multi-billion-dollar expansion of a major Australian coal port.

An announcement was expected from Environment Minister Mark Butler on Friday but has still not come, with the man about to make the call on one of the country’s biggest infrastructure projects delaying his decision, possibly for months.

The Federal Environment Minister said he had “only just received a number of reports, potentially impacting the assessment process” when pressed for a decision late on Friday. The tense wait continues for environmental campaigners, who say the project would have a devastating and far-reaching impact on the World Heritage area.

Mr Butler has indicated the planning may enter another round of consultation, possibly taking more than three months.

In independent report released into the planned dredging over the weekend says it could be possible to carry out works without destroying the fragile nearby ecosystem.

A review of developments in their current economic and historical contexts chaired by Sydney Harbour Federation Trust chair Anthea Tinney has said: “Community confidence in the environmental performance of approved developments within the port is generally low; however, it appears from the evidence available that compliance and enforcement is being managed in an appropriate way.”

One of the pillars of the arguments against the Abbot Point coal port expansion is a recent spate of mysterious disease in local aquatic life, which has been linked by some to current industrial works at the Gladstone port, among other areas. The report says that marine life deaths and skin conditions “are likely to be the result of multiple pressures, including extreme weather events and associated overcrowding from fish that moved into the area after overspilling Awoonga Dam.”

Neither branch of government has yet responded to the report, which for the most part is in favour of the expansion. It does highlight the important point that as the port was built in 1955 and the Reef only declared a World Heritage area in 1981, there should be consideration for contemporary views of the contribution of the natural site.