Updated

Australia approved a plan to dump large amounts of mud and sediment into the oceans surrounding the Great Barrier Reef -- making room for developers to expand a coal port on the country's eastern coast on Friday.

Environmentalists say the decision made by the government agency that oversees the Reef will endanger one of the world's most fragile ecosystems.

"This is a sad day for the Reef and anyone who cares about its future," World Wildlife Fund Great Barrier Reef campaigner Richard Leck said in a press release.

The federal government in December approved the expansion of the Abbot Point coal port in northern Queensland, which requires a massive dredging operation to make way for ships entering and exiting the port. About 106 million cubic feet of dredged mud will be dumped within the marine park under the plan.

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

More On This...

But outraged conservationists say the already fragile reef will be gravely threatened by the dredging, which will occur over a 455-acre area. Apart from the risk that the sediment will smother coral and seagrass, the increased shipping traffic will boost the risk of accidents, such as oil spills and collisions with delicate coral beds, environment groups argue.

On Friday, the Great Barrier Reef Marine Park Authority — the government manager of the 133,360 square mile protected marine zone — approved an application by the state-owned North Queensland Bulk Ports Corp. for a permit to dump the sediment within the marine park in a location that does not contain any coral or seagrass beds.

Bruce Elliot, general manager for the marine authority's biodiversity, conservation and sustainable use division, said in a statement that strict conditions would be placed on the sediment disposal, including a water quality monitoring plan that will remain in place five years after the dumping is complete.

"By granting this permit application with rigorous safeguards, we believe we are able to provide certainty to both the community and the proponent while seeking to ensure transparent and best practice environmental management of the project," Elliot said.

But environmentalists with the WWF were unconvinced that the Reef would be adequately protected.

"The World Heritage Committee will take a dim view of this decision which is in direct contravention of one of its recommendations. Committee members could decide at their June meeting in Doha to list the Reef as ‘World Heritage in Danger," Leck said.

The ports 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," Fish said in an interview last month. "We're just relocating it from one spot to another spot, in a like-per-like situation."

Rachel Campbell, spokeswoman for the ports corporation, said the group didn't anticipate the conditions would cause any delays to the dredging plans.

Australia is home to vast mineral deposits and a mining boom fueled by demand from China kept Australia's economy strong during the global financial crisis. Though the boom is now cooling as demand from China slows, Prime Minister Tony Abbott and his conservative government have vowed to focus their efforts on reviving the industry.

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.

In response, 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 at the time. "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 coral-eating crown of thorns starfish.

"We are devastated. I think any Australian or anyone around the world who cares about the future of the reef is also devastated by this decision," said Leck. "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."

The Associated Press contributed to this report.