Sea Shepherd is planning to keep up its fight against Japanese whaling in the Southern Ocean.
Japan has advised it will resume whaling there, despite an international court finding it was unlawful.
The decision has appalled John Key, who won't rule out New Zealand taking further legal action.
Spokesman Jeff Hansen said a Sea Shepherd ship will be heading to the Southern Ocean at the end of next week.
"We were looking at an anti-poaching campaign of illegal fishing, however any illegal activity that we come across in the Southern ocean, we will engage."
John Key is hoping to raise the issue with prime minister Shinzo Abe during this week's Paris climate talks.
Labour leader Andrew Little thinks the Government should be more proactive in protecting the Southern Ocean.
"We've left it up to private organisations like Sea Shepherd in the past, but actually we have a responsibility, because we're the ones that sign up to the international whaling agreement."
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