Japan and pro-whaling allies have struck an historic blow against the moratorium on commercial hunting, winning their first vote in two decades at global whale talks.

The pro-whaling block was triumphant after forcing a resolution which branded the ban “no longer necessary” through the International Whaling Commission (IWC) annual meeting with a razor-thin one-vote margin. Though the non-binding resolution does not mean the 20 year-old moratorium will be overturned, the vote is a symbolic triumph for countries determined to eventually resume commercial whaling.

Environmentalists at the IWC meeting in the Caribbean state of St Kitts and Nevis called the vote “tragic.”

“This is the most serious defeat the conservation cause has ever suffered at the IWC,” New Zealand conservation minister Chris Carter told reporters.“It has been a significant diplomatic victory for Japan.”

Japan and allies savoured the first fruit of a relentless diplomatic campaign to turn the body away from pure conservation and back to what Tokyo calls sustainable whaling.

“This is a historic event,” said Joji Morishita, Japan’s top IWC delegate, who vowed not to take revenge on anti-whaling opponents Australia, Britain, New Zealand and the United States.

A “historical turning point was taken, however the polarised situation of the IWC will remain,” he said. A spokesman for Japan’s delegation, Glenn Inwood, said “this is the first serious setback the global moratorium has ever had. It is only a matter of time before it is gone completely.”

Environmental campaigners were left reeling from the blow, as pro-whaling states on the IWC vowed to mount a legal challenge.

“This is the most significant setback since (the moratorium) came into force,” said Kitty Block, a lawyer with Humane Society International.“We are sickened and disappointed,” said Joanna Benn of global conservation group WWF.

Patrick Ramage of the International Fund for Animal Welfare (IFAW) accused Japan of underhand tactics.

“Japan wants to kill whales, they are willing to kill the IWC to do it.” Niki Entrup of the Whalewatch coalition warned “this tragic moment ... is a return to the 1970s dark days where whales roamed the seas unprotected. The world must wake up from its great slumber.”

The resolution said that the moratorium on commercial hunting “which was clearly intended as a temporary measure is no longer necessary.”

But the moratorium, enforced since 1986, still stands because it needs a 75 per cent super-majority to be overturned. 

The new measure, known as the St Kitts and Nevis resolution, passed by 33 to 32 votes with one abstention. 

Its text also argued that whales depleted fish stocks, and that some non-governmental organisations were guilty of using “threats” in the anti-whaling campaign. 

Japan abides by the moratorium but conducts some “research” whaling through what opponents say is a loophole in the IWC charter, as does Iceland. Norway ignores the moratorium altogether. Around 2,000 whales are taken a year by the three nations. 

Japan hopes to use the resolution as a political weapon, wielding it to argue that more states than not on the 70-nation IWC body believed the commercial whaling ban should be lifted. 

It has complained that anti-whaling states have deadlocked the commission, which was set up in 1946 to prevent whales from passing into extinction through over hunting. 

Securing a permanent majority on the IWC would allow Tokyo to control the commission’s agenda for the first time since a moratorium was introduced and, environmentalists fear, let Tokyo frustrate conservation efforts. 

The five-day meeting ends today.