The agency that oversees Australia's Great Barrier Reef has given permission for large amounts of dredged mud to be dumped close to the reef.
The disposal of about three million cubic metres of spoil is part of a project to create a major coal port at Abbot Point south of Townsville on the Queensland coast.
Late last year, the Australian government approved an application for the coal terminal to be expanded. The dredging is needed to allow ships into the port, the BBC reports.
Environmentalists say one of the world's most fragile ecosystems is being treated like a rubbish tip. Earlier this month, 233 scientists signed a letter urging the Great Barrier Reef Marine Park Authority to reject the plan to dump the spoil.
In a statement the reef authority said the seafloor of the approved disposal area does not contain coral reefs or seagrass beds, and its chairman, Russell Reichelt, said the mud being desposited in the area is safe.
"The dredged material is 70 percent sand, 30 percent fine silts and clays. It's come down the rivers over the past few thousand years and it has no toxic material in it."
Conditions imposed by the reef authority include limits on when the spoil can be dumped, a long-term water quality monitoring plan and compensation for commercial fishers in the event of adverse impacts, the ABC reports.
Louise Matthiesson of Greenpeace says the conditions are not good enough and it will continue lobbying against the port's expansion.
She said the World Heritage Committee would take a dim view of the decision when considering whether to list the reef as "in danger".