Australia on Thursday announced it will create the world's largest network of marine sanctuaries, with limits placed on fishing, oil and gas exploration off the coast.

The new reserves cover 3.1 million square kilometres, or more than one-third of Australian waters, taking in significant marine breeding and feeding grounds.

The announcement, after years of planning and consultation, came ahead of the Rio+20 Conference on Sustainable Development next week in Brazil, which Environment Minister Tony Burke and Prime Minister Julia Gillard will attend.

"It's time for the world to turn a corner on protection of our oceans," Burke said. "And Australia today is leading that next step.

"This new network of marine reserves will help ensure that Australia's diverse marine environment, and the life it supports, remain healthy, productive and resilient for future generations."

The network will increase the number of marine reserves from 27 to 60, expanding protection of creatures such as the blue whale, green turtle, critically endangered populations of grey nurse sharks, and dugongs.