The Indian Ocean archipelago of the Maldives announced at the Rio+20 summit here Wednesday it would create the world's biggest marine reserve to protect its fisheries and biodiversity.

"I would like to announce today Maldives will become the first country to become a marine reserve," President Mohamed Waheed said in a speech.

"It will become the single largest marine reserve in the world. This policy will allow only sustainable and eco-friendly fishing. It will exclude deep-sea, purse-seining and other destructive (trawling) techniques," he said.

He was referring to a fishing technique in which a seine in the shape of a bag is used to ensnare fish and other catch.

Waheed added: "Already, Maldives is a sanctuary for sharks, turtles and many species of fish in the Indian Ocean. Trade in these products is now illegal in the Maldives."

He did not spell out how big the reserve would be, but said, "We can do it in a short time. I hope we can do it in five years."

Sue Lieberman, deputy director of the Pew Environment Group, a US non-governmental organization, said the announcement was "highly significant... and a great commitment," given that a marine reserve carried a much tougher status than a marine-protected area.

"Technically, a marine reserve is like where there is no extractive use, there is no industrial fishing, no mining. It doesn't mean no recreational fishing or boating," she told AFP.

"It's like, on land, having a national park."

"What he said implies their whole EEZ, although we'll wait to hear more," she said.

The EEZ -- exclusive economic zone -- is the area of sea that can be claimed by a country to exploit its marine resources, to a limit of 200 nautical miles around its coasts.

"Maldives may be a small (set of) island(s) but it's a large country when you count their ocean," she said.