A DECISION on whether to approve a fourth LNG plant on Gladstone's Curtis Island has been delayed until December.
Federal Environment Minister Greg Hunt has given himself more time to decide whether to allow the Arrow gas plant to be built.
Mr Hunt was due to make a decision on the project on Wednesday, but has pushed the deadline back to December 13.
A spokesman from his office said this would allow more time for "further consideration".
Arrow Energy's plan to build the plant was given state approval in September.
The Australian Marine Conservation Society on Tuesday called on Mr Hunt to reject the proposed plant.
Great Barrier Reef campaign director Felicity Wishart said the fourth plant would require substantial additional dredging.
"That's going to mean more suspended sediment in the water, more risks to turtles, dugongs and coral and more threats to tourism," Ms Wishart said.
"It will also increase the number of massive LNG ships crisscrossing the Great Barrier Reef.
"Curtis Island is within the reef's World Heritage Area yet its mangroves and beaches are being destroyed to build gas processing plants.
"The three gas hubs already under construction are suffering from major cost overruns and there are questions about whether there is enough supply of gas to make all these processing plants viable."
"The last thing that Queensland needs is a fourth gas plant that damages the Reef and fails to deliver economic benefits to the state.