Australia has approved a plan to dump millions of tons of sediment near the Great Barrier Reef as part of a major coal port expansion — a decision that environmentalists say will endanger one of the world's most fragile ecosystems.

The Great Barrier Reef Marine Park Authority rubber-stamped the federal government's approval of the expansion of the Abbot Point coal port in northern Queensland, which requires a massive dredging operation to expanded access.

Almost 3 million cubic meters of dredged mud will be dumped within the marine park under the plan.

Greg Hunt, the environment minister, has vowed that "some of the strictest conditions in Australian history" would be in place to protect the reef, including water quality measures and safeguards for the reef's plants and animals.

The government added that no mud would be dumped directly on coral. However, conservationists say the already fragile reef will still be gravely threatened by the dredging.

The sediment endangers coral and sea grass, they say, and increased shipping traffic heightens the risk of accidents, such as oil spills and collisions with delicate coral beds.

The port corporation's CEO, Brad Fish, has argued that the sediment has been extensively tested for contaminants and was found to be clean.

"This is natural sand and seabed materials ... It's what's already there," he said last month. "We're just relocating it from one spot to another spot, in a like-per-like situation."

In a report released in 2012, UNESCO expressed concern about development along the reef, including ports, and warned that the marine park was at risk of being listed as a World Heritage site in danger.

The Queensland premier, Campbell Newman, said his government would protect the environment — but not at the expense of the state's economy.

"We are in the coal business," he said in December, "If you want decent hospitals, schools and police on the beat, we all need to understand that."

Environmentalists were infuriated by Friday's decision, saying that the reef is already vulnerable, having lost huge amounts of coral in recent decades to storm damage and the coral-eating crown of thorns starfish.

Felicity Wishart, of the Australian Marine Conservation Society, told Al Jazeera that there were concerns the dumping would have serious health effects on the reef.

"When you dump sand and sediment, a lot of it is suspended in the water. It will travel out to the reef, and that is our concern. The sediment will cut out light and make it much more difficult for sea grass and coral to survive."

"The Great Barrier Reef is already suffering poor health from the effects of urban development and runoff from farming. To add dredging is adding insult to injury. Its condition will worsen."

"We will look to see what legal action we can take. We will be putting pressure on companies involved. But we have a long way to go."

Richard Leck, reef campaign leader for international conservation group WWF said that the organization was devastated.

"I think any Australian or anyone around the world who cares about the future of the reef is also devastated by this decision," he said. "Exactly the wrong thing that you want to do when an ecosystem is suffering ... is introduce another major threat to it — and that's what the marine park authority has allowed to happen today."

Al Jazeera and wire services