The New Zealand government on Monday hit out at Japan for defying the international community in resuming whaling in the Southern Ocean.

Foreign Minister Murray McCully said the Japanese whaling program in the Southern Ocean also served no legitimate scientific purpose.

"New Zealand has long-standing and deep-seated concerns about whaling in the Southern Ocean and we urge Japan to reconsider this year's hunt," McCully said in a statement.

"It is clear that Japan's research objectives can be met using nonlethal means and at the recent International Whaling Commission meeting the majority of members present agreed that Japan had not demonstrated the scientific justification for lethal whaling."

McCully's statement added: "The Southern Ocean is one of the world's last great pristine wilderness areas. Japan's decision to continue whaling there, at a time when we are celebrating conservation efforts in the region, puts Japan well out of step with international opinion on this issue."

International anti-whaling activist group Sea Shepherd Global has warned it is sending vessels to the Southern Ocean to obstruct the Japanese whaling vessels, prompting concerns for the safety of whaling and anti-whaling crews.

In January, the governments of New Zealand, Australia, the Netherlands and the United States issued a joint statement attacking Japan's whaling in the Southern Ocean over the last southern summer and calling for protesters and whalers to act safely.

It said the four governments remained resolutely opposed to commercial whaling, in particular in the Southern Ocean Whale Sanctuary established by the IWC.

In 2014, the International Court of Justice issued a judgment that found Japan's "scientific" JARPA II whaling program was not for the purposes of scientific research and must cease.

The same year, the IWC passed a New Zealand resolution enshrining the court's decision and imposing limits on future scientific whaling permits, requiring nonlethal alternatives to be considered for any approved scientific research on whales.

After a one-year hiatus from whaling, the Japanese fleet returned to the Antarctic last season and slaughtered 333 minke whales, more than half of them pregnant females, according to Sea Shepherd Global.