WELLINGTON, Oct. 20 -- The New Zealand government is to try for a fourth time to have the Antarctic's Ross Sea turned into the world's largest marine reserve, Radio New Zealand reported Monday.

If the attempt was successful, 1.32 square km of ocean would be protected, but all 25 other members of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) would have to agree to it at a meeting in Tasmania, Australia, this week.

Russia and Ukraine have opposed the past three attempts citing concerns about the size of the reserve and also about proposed fishing restrictions.

The report cited an unspecified Ministry for Foreign Affairs and Trade source as saying support for the proposal was continuing to grow, but a resolution remained difficult.

Environmental campaigners expressed doubts that Russia and Ukraine would ever agree to a marine protected area (MPA) after the failure of the last proposal -- jointly tabled by New Zealand and the United States -- in October last year.

The original proposal had been for a Ross Sea marine protected area of 2.3 million square km, including a "fully protected" area of 1.6 million square km.

Talks on two reserve proposals by the CCAMLR stalled temporarily in July last year when the Russian delegation questioned the CCAMLR's legal authority to declare such reserves.

The CCAMLR had been considering two MPA proposals: the New Zealand-U.S. proposal for the Ross Sea region and another by Australia, France and the European Union for a network of MPAs in east Antarctica.