Japan's plans to resume a controversial Antarctic whale hunt in the name of research, which opponents say is really just for the meat, came under scrutiny in Slovenia on Tuesday.

As members of the International Whaling Commission (IWC) met for a second day, the agenda was laden with contentious issues that seek to balance national whaling traditions with conservation needs.

Japan has no formal proposal before the commission, but was forced into the spotlight by a New Zealand proposal that no permits be issued for whaling research in future without proof of scientific necessity.

"The New Zealand proposal would make it very difficult for Japan to come up with a scientific programme" acceptable to the commission, said Kitty Block of the Humane Society International, an observer at the talks.

Tokyo's eye on the Antarctic tops the list of hotly disputed topics for the IWC's 65th meeting in the Adriatic resort of Portoroz until Thursday.

It is the commission's first meeting since the United Nations' highest court found in March that Japan abused an exemption to a commercial whaling ban for scientific research purposes.

Japan cancelled its 2014/15 Antarctic hunt after the ruling, but a fisheries official told AFP his country would "explain its plan to resume research whaling in the next season (2015/16)" at the IWC meeting.

The country killed more than 250 minke whales in the Antarctic in the previous season.

- Challenge on science -

New Zealand's draft resolution, supported by European nations, Australia and the United States, among others, recalls the International Court of Justice's (ICJ) finding that any state seeking to kill whales for research must show why non-lethal methods were not an option.

And it wants the commission to instruct its scientific committee to thoroughly examine future research bids within the strict parameters set by the court.

"The ICJ decision is an important ruling regarding how you assess a scientific programme," said New Zealand commissioner Gerard van Bohemen.

Japanese representative Hideki Moronuki, however, told AFP: "New Zealand's understanding of the ICJ judgement differs from Japan's... Japan cannot accept the resolution as it now stands."

But he said the delegation was "willing to work with New Zealand and other countries tonight to find common ground. We hope that some agreement can be reached."

Discussion on a second contentious issue has been put on hold -- a fresh attempt to create a whale sanctuary in the South Atlantic.

The idea, proposed by Argentina, Brazil, South Africa and Uruguay, has been thwarted by pro-hunting nations for years.

It requires 75 percent of votes to pass but failed at previous commission meetings, including the last one in Panama in 2012 where it mustered 64 percent.

The plan is backed by European countries and the United States, but Japan rejects the idea "from its basic position of seeking to resume sustainable commercial whaling", according to the fisheries official.

Two whale sanctuaries already exist, one in the Indian Ocean was created in 1979 and a second in 1994 in the Southern Ocean around Antarctica, where Japan has continued annual hunts in the name of science.

On the first meeting day on Monday, the IWC gave aboriginal Greenlanders the go-ahead to kill hundreds of whales, while Iceland came under fire for contravening a ban on commercial hunting.

Greenland's hunts are allowed under a special aboriginal subsistence dispensation, but conservationists fear much of the meat was actually being sold.

Iceland and Norway, on the other hand, issue commercial permits under objections or reservations registered against the IWC's whaling ban, and together catch hundreds of whales per year.

Also still to be discussed is Japan's bid to be allowed small-scale whaling off its own coast.