The International Whaling Commission has approved a New Zealand proposed resolution to tighten the rules around research whaling at a meeting in Slovenia overnight.
The forum passed a key resolution to uphold the recent World Court ruling that Japan's scientific whaling in Antarctica was illegal and no further permits should be issued, the International Fund for Animal Welfare (IFAW) said.
The resolution was pushed to a vote, which went through 35-20 with five abstentions and one absence.
IFAW global whales programme director Patrick Ramagetor said the result was a "crucial victory for whales".
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"After the recent historic World Court ruling it begged the question of whether the IWC would be up to the challenge of imposing court-ordered standards for scientific whaling or content to stand on the sidelines while Japan continued commercial whaling by another name.
"We now urge Japan to call a permanent end to its illegal whaling activities in the Southern Ocean."
After initially announcing it would comply with the ruling in March and cancel its slaughter in the Southern Ocean Whale Sanctuary, Japan stated its intention to create a new research plan and resume killing of whales in the name of science after a one-year pause, Mr Ramagetor said.