A key meeting on whales opened to early confrontation Monday with Japan seeking an end to a 30-year moratorium on whale hunting, and others proposing an Atlantic cetacean sanctuary.

While meeting host Slovenia urged compromise for the marine mammals' sake, member states of the International Whaling Commission (IWC) cleaved almost immediately into historic pro- and anti-hunting factions.

"The moratorium on commercial whaling should and could be lifted on a stock-by-stock basis based on sound scientific evidence," said Japan's written opening statement to the commission's 66th meeting.

The commission's own advisory scientific committee "has confirmed that certain stocks of whale species are recovered", which implies the moratorium is outdated, Japan argued.

One of the biggest disputes among the IWC's 88 member countries is Japan's yearly whale hunt in the name of science - for which an exception exists under IWC rules - but which critics insist sustains the country's whaling industry.

The meat ends up on supermarket shelves and in restaurants, in line with an IWC stipulation that whales taken for science must be eaten.

The International Court of Justice ruled in 2014 that Japan was abusing the scientific exemption.

Tokyo cancelled its 2014/15 hunt, only to resume it the following year, killing an estimated 300-plus animals.

New Zealand and Australia will ask the IWC this week to put a rigorous process in place to review whaling for science.

"It is clear that Japan's stated research objectives can be met using non-lethal means and we urge Japan to cease its lethal practices," New Zealand's opening statement read.

Japan, in turn, opposes the creation of a South Atlantic whale sanctuary, a proposal of Argentina, Brazil, Gabon, South Africa and Uruguay which carries the backing of the European Union and others.

Japan, Norway and Iceland are traditionally in their own corner at the biennial IWC meetings, which seek to balance issues of national sovereignty, subsistence rights and culture with conservation of Earth's natural bounty.

Norway and Iceland have registered objections to the moratorium, and continue commercial whaling.

This year's meeting marks the 70th anniversary of the commission's founding, and the 30th birthday of the whaling moratorium estimated to have prevented the killing of tens - even hundreds - of thousands of whales.

Conservationists say whales still face a multitude of perils, from meat hunters and ship strikes to getting snared in fishing gear and injury from powerful submarine sonar.

"In spite of the fact that the contracting states have different views on the conservation and management of whales, it is in the interests of all of us to give back to the cetaceans their living environment," Slovene Environment Minister Irena Majcen told Monday's opening.

"This is something that should unite us."