Australia will more than double an area near the Great Barrier Reef subject to special curbs on shipping in a bid to protect the environmentally sensitive region, the government said on Saturday.

The decision to include large areas of the adjacent Coral Sea in the area will expand it by 140 percent, or 565,000 square km (218,000 square miles), Infrastructure Minister Warren Truss said in a statement.

The expansion comes as international concern is growing over the reef with the U.N. Educational, Scientific and Cultural Organization (UNESCO) considering putting it on its list of World Heritage sites that are "in danger".

"The Coral Sea is one of the world's most distinctive and undisturbed marine ecosystems," Truss said. "It behoves us to do all we can to reasonably and responsibly protect one of our greatest natural resources."

"Our new measures enhance protection for the Coral Sea - as well as the adjacent Great Barrier Reef World Heritage area - by helping ships traverse the region safely and avoid potentially hazardous areas." Proposals put forward by Australia last year were accepted by the International Maritime Organization (IMO) at a meeting in London overnight, Truss said. The changes should gradually come into force once associated measures are adopted by an IMO committee expected to be held next month. Busy shipping lanes pass through the area and commercial ships are required to hire a special "reef pilot" to navigate through it.

Truss said the changes would ultimately involve a new "area to be avoided" and two-way shipping lanes to keep ships away from reefs, sandbars and shoals. In 2010 a Chinese coal carrier ran aground in the Great Barrier Reef, provoking an international outcry.

Since then, there has been renewed concern that development, particularly coal mining in Australia's northeastern state of Queensland, could endanger the reef.

UNESCO is due to make its decision on whether to list the reef as in danger, which would be an embarrassment for Australia, next month, after deferring a decision for 12 months in June last year.

The Coral Sea is an area of the western Pacific stretching out from the Great Barrier Reef to the Solomon Islands, Vanuatu and New Caledonia.