The world's whaling watchdog agreed Thursday to toughen scrutiny of Antarctic hunts which Japan conducts in the name of science, but rejected a bid to expand protection in the South Atlantic.

The issues were put to a vote on the closing day of the International Whaling Commission's (IWC) 65th meeting -- its controversy-laden agenda seeking to balance traditional hunting rights with conservation.

It was the panel's first meeting since the International Court of Justice (ICJ) ruled in March that Japan had abused a scientific exemption to a 1986 commercial whaling ban.

Critics accuse Japan, the only country to invoke the exemption, of covering up commercial hunts.

On Thursday, nations present at the meeting approved with 35 votes to 20, with five abstentions, a New Zealand resolution to tighten the review of proposals for research whaling.

But Japan and other whaling nations prevailed in their opposition to the creation of a sanctuary in the South Atlantic.

That proposal needed 75 percent of votes to pass but got only two-thirds.

- Victory claimed -

Conservationists hailed the New Zealand resolution as a major victory for whales.

It instructs the IWC's scientific committee to assess whether a research bid is truly science-driven, including by satisfying itself that non-lethal means are not an option.

Pending such review, the document "requests" that countries do not issue any research whaling permits.

"This measure goes a long way in securing the full promise of the ICJ Judgment which gives whales in Antarctica protection against slaughter for the first time in more than a century," said Patrick Ramage, director of the International Fund for Animal Welfare's global whales programme.

Tokyo cancelled its 2014-15 Antarctic hunt after the court ruling, but has said it intends to resume "research whaling" in 2015-16 and will file a new "plan" by the end of this year.

"The resolution does not ban whaling and does not ban scientific research whaling. It does not have that power," Japan's alternate commissioner Hideki Moronuki said on Thursday.

"The world's whale populations are able to handle sustainable whaling, especially the minke whale stocks in the Antarctic which the IWC has agreed are in good health.

"So we want our science and future science to underpin reliable management and catch quotas, and we expect the IWC to implement this."

Japan killed more than 250 minke whales in the Antarctic in the 2013-14 season and 103 the previous year.

It also conducts hunts in the name of science in the Northwest Pacific, where it killed 132 whales in 2013, and off the Japanese coast, where it caught 92.

While the commission's scientific committee weighs proposals for scientific whaling, there is nothing preventing a nation from going ahead without its blessing.

On Thursday, commission members also voted down a Japanese bid to be allowed to carry out small-scale commercial whaling off its own coast.

There was widespread disappointment, however, at the failure of a proposal from Argentina, Brazil, South Africa and Uruguay, countries which depend on whale-watching tourist dollars, for the creation of a South Atlantic sanctuary.

"Such sanctuaries are important safe havens for whales in an increasingly threatened environment," said the Humane Society International's Rebecca Regnery.

The sanctuary bid has failed at several previous meetings as well.

In another decision lamented by anti-whalers, the IWC on Monday gave aboriginal Greenlanders the go-ahead to kill hundreds of the animals.

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

Iceland also found itself coming under fire.

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