CANBERRA, Australia - Two American fighter jets dropped four unarmed bombs into Australia's Great Barrier Reef Marine Park last week when a training exercise went wrong, the U.S. Navy said, angering environmentalists.

The two AV-8B Harrier jets launched from the amphibious assault ship USS Bonhomme Richard each jettisoned an inert practice bomb and an unarmed laser-guided explosive bomb into the World Heritage-listed marine park off the coast of Queensland state on Tuesday, the U.S. 7th Fleet said in a statement Saturday.

Commander William Marks, spokesman for the 7th Fleet, said the emergency jettison was made in consultation with Australian officials.

"There is minimal environmental impact," Marks told Australian Broadcasting Corp. radio on Monday. "It is a safe situation for the environment, for shipping, for navigation."

The four bombs, weighing a total of 2,000 pounds, were dropped into more than 164 feet of water away from coral to minimize possible damage to the reef, the statement said.

None of the bombs exploded, the statement said.

The jets from the 31st Marine Expeditionary Unit had intended to drop the ordnances on the Townshend Island bombing range, but aborted the mission when controllers reported the area was not clear of hazards, the statement said.

"There were civilian boats right below them," Marks said.

The pilots conducted the emergency jettison because they were low on fuel and could not land with their bomb load, the Navy said.