New Zealand Prime Minister John Key said on Monday that his government would not resort to court action to stop whaling in the Southern Ocean, as Australia has threatened, unless diplomacy failed.

"Either the diplomatic solution is going to be a stunning success in the next few months or it's going to be a stunning failure," Key told Radio Newstalk-ZB on Monday.

He said Australia was still pursuing a diplomatic outcome.

New Zealand Foreign Minister Murray McCully said that negotiations are underway.

New Zealand's opposition Labor Party foreign affairs spokesman Chris Carter on Sunday called on the government to back Australian Prime Minister Kevin Rudd's position on whaling: either Japan stops killing whales in the Southern Ocean by November or Australia will take it to the International Court of Justice (ICJ).

McCully said that the government's preference was to continue down the diplomatic path.

McCully said if a diplomatic solution could be reached, more whales would be saved.

The International Whaling Commission (IWC) adopted a moratorium on whaling in 1982 when many whale species were facing extinction. A 75 percent majority at the IWC is required to overturn the moratorium.

Japan uses a provision in the International Convention for the Regulation of Whaling which allows whales to be killed for scientific research to kill about 1,000 a year.

Meanwhile, New Zealand anti-whaling protester Peter Bethune remains on the Japanese vessel Shonan Maru II which he boarded on Feb. 15.

Bethune boarded the Japanese ship to demand a 3 million NZ dollars (2.1 million U.S. dollars) payment for the Ady Gil, which sank after a collision with the whalers.