JAKARTA: Indonesia on Friday became home to the world's biggest manta ray sanctuary covering millions of square kilometres, as it seeks to protect the huge winged fish and draw more tourists to the sprawling archipelago.

New legislation gives full protection to the creatures across all the waters surrounding Southeast Asia's biggest country, which for years has been the world's largest shark and ray fishery.

Protection group Conservation International hailed the “bold” move and said it was influenced by a recent government-backed review that showed a single manta ray was worth one million dollars in tourism revenue over its lifetime.

This compares to between $40 and $500 if caught and killed, the group said.

Many foreign tourists come to Indonesia every year to dive in some of the world's most bio diverse waters and manta rays are a favourite sight.

The gentle beasts have wingspans up to 25 feet (7.5 metres), which they flap to propel themselves gracefully through the water.

“Indonesia now has the second-largest manta ray tourism industry in the world, with an estimated annual turnover of $15 million,” said Agus Dermawan, a senior official from the ministry of marine affairs and fisheries.

“Given the huge area of reefs and islands in our country, if managed properly, Indonesia could become the top manta tourism destination on the planet.”

Indonesia is one of the few places in the world where tourists can easily see both species of manta rays, the oceanic and reef varieties.

The new legislation protects both.

Taking tourists out to view rays and other creatures provides livelihoods for many people working in popular dive spots across Indonesia, such as Raja Ampat off the northwest tip of New Guinea island and around the resort island of Bali.

In recent years their numbers of rays have declined rapidly, however, due to voracious demand in China for their body parts for use in traditional medicine.

The new legislation protects manta rays within Indonesia's 5.8 million square kilometres (2.2 million square miles) of ocean, banning fishing of the rays and their export.

It came a year after the local government in Raja Ampat announced the creation of a 46,000-square-kilometre shark and ray sanctuary.

The International Union for Conservation of Nature classifies both species of manta ray as vulnerable.