A picture from the Great Barrier Reef Marine Park Authority showing an Algal overgrowth section of the reef. A broken-down cargo ship was drifting towards Australia's Great Barrier Reef Saturday, with fears of major damage if it were to run aground at the World Heritage-listed site.

A broken-down cargo ship was drifting towards the fringes of Australia's Great Barrier Reef Saturday, with fears of major damage if it were to run aground at the World Heritage-listed site.

Authorities were rushing to the assistance of the Hong Kong-flagged bulk carrier, the ID Integrity, which broke down north of Cairns.

The Australian Maritime Safety Authority (AMSA) said the ship had suffered an "an engine breakdown en route from Shanghai" and was adrift on what is the world's biggest coral reef.

"The crew is currently attempting to repair the engine, in the hope that the vessel will be able to resume its passage," AMSA said in a statement.

"Contingency planning is under way in case the crew cannot get the engine restarted."

An emergency towing ship, the Pacific Responder, has been dispatched to the Coral Sea along with two tug ships but the first vessel would not reach the unladen ID Integrity until Sunday morning.

An image from NASA's Earth Obeservatory Internet site of the Great Barrier Reef, extending for 1,242 miles (2,000 km) along the northeastern coast of Australia. The Australian Maritime Safety Authority (AMSA) says the ID Integrity is drifting towards the reef after suffering "an engine breakdown en route from Shanghai".

The ship managed to pass over Shark Reef late Saturday night "with no damage sustained" by managing its ballast, but it continued to drift west towards the Outer Reef, on the edge of the main reef body, AMSA added in a later update.

"Emergency tugs will rendezvous with the ID Integrity late Sunday morning," the maritime authority said.

ID Wallem confirmed to AFP that the vessel "has now cleared the Shark Reef without incident.

It said the vessel was expected to drift in open water until the first tug arrived and "there should be no risk to the Great Barrier Reef".

The firm earlier played down the risk of the Integrity running aground and stressed that there was no cargo on board or pollution associated with its engine problems.

"There is no pollution and no injuries and the ship manager is working closely with all authorities notified," the ship management firm said.

"The ship manager and crew of the vessel will continue to work to quickly restore power and take measures to avoid any environmental impact in Australian waters."

It is not the first time a freighter has run into trouble on the Barrier Reef. The Chinese-registered coal carrier Shen Neng 1 foundered in April 2010 leaking tonnes of heavy fuel oil and threatening an ecological disaster.

While a major catastrophe was ultimately avoided, the huge ship gouged a three kilometre-long (1.8 mile) scar in the world's biggest coral reef. The vessel was stranded for nine days before salvagers could refloat it.

Senator Larissa Waters from the environmentally-driven Greens party said Saturday's breakdown was a reminder of the dangers of turning the reef into a "coal and gas superhighway" to Asia.

"While we all wait and hope that this ship can be rescued before it creates a disastrous spill, the Australian government should now take responsibility for the Great Barrier Reef and stop this headlong rush to boost fossil fuels exports at the expense of the climate and the environment," she said.

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(c) 2012 AFP