SYDNEY (AFP) - Leonardo DiCaprio urged a high-level Antarctic conservation meeting in Australia Tuesday to approve a sweeping Southern Ocean marine sanctuary to protect thousands of polar species.

The Hollywood star wrote an email to supporters of activist group Avaaz calling for a “people-powered surge” in favour of the sanctuary, which is headlining talks at the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

The key theme of the 2012 CCAMLR summit, which officially opened in Hobart on Tuesday, is the establishment of a representative system of marine protected areas in the Southern Ocean as proposed by Australia, France and the EU.

The region is home to big populations of penguins, seals and whales found nowhere else on Earth, and also has unique seafloor features that nurture early links in the food chain, according to environmental groups.

DiCaprio said most countries backed a marine haven off East Antarctica which, if approved in the size being advocated by green groups, would be the world’s largest ocean sanctuary sprawling over an area twice the size of India.

“But Russia, South Korea and a few others are threatening to vote it down so they can plunder these seas now that others have been fished to death,” he said, advocating an online petition with more than 842,000 signatures.