Oil that leaked from a coal-carrying ship stranded on the Great Barrier Reef has dispersed into the ocean, and crews prepared Thursday to transfer the ship's remaining oil to eliminate any further environmental risk to the world's largest coral reef.

The water surface no longer has an oil sheen around the Shen Neng 1 and the leak from the hull had stopped, said Patrick Quirk, general manager of Maritime Safety Queensland.

"We have our spray aircraft on standby if more oil leaks, and it was effective when used in the early stage of the incident," Quirk said in a statement.

The bulk carrier was taking coal to China from the Queensland port of Gladstone when it crashed full speed into Douglas Shoal on Saturday. Coral shredded one part of the ship, and three or four tons of oil leaked from a ruptured fuel tank.

Containment booms now surround the ship, and crews worked this week to transfer the remaining fuel oil to safer compartments within the ship. Two tugboats are holding the Shen Neng 1 steady, keeping it from rocking with waves, and a bunker barge is in place to take on the fuel oil.

Officials aim to refloat the ship and escort it from Australian waters, but first they must transfer nearly 950 metric tons of heavy fuel oil off the boat to prevent more spills.

Environment Minister Peter Garrett, who took an aerial tour of the site Thursday, said the oil transfer was a "critical phase" in managing the accident.

"Oil is the substance that will pose the greatest threat to the ecology of the Great Barrier Reef, and the operation to successfully get oil from the vessel onto the bunker will significantly reduce that risk," Garrett told reporters. "It's still going to take some time."

Maritime and state officials are on board the Shen Neng 1 to interview the crew and determine how the crash occurred.

Garrett said vessels should be tracked through the reef's shipping corridors.

Prime Minister Kevin Rudd said Tuesday that he would consider implementing stricter shipping regulations within the reef's boundaries.

The Great Barrier Reef is a World Heritage site because of its gleaming waters and environmental value as home to thousands of marine species.

The accident occurred in the southern tip of the reef, which is not the main tourism hub.

- AP