A blog by Labour's foreign affairs spokesman Chris Carter has been blamed for the cancellation of a government briefing to opposition parties on international whaling negotiations.

Mr Carter said Foreign Affairs Ministry officials and New Zealand's International Whaling Commission (IWC) representative, Sir Geoffrey Palmer, were due to give the briefing today, but had pulled out because of concerns from Foreign Minister Murray McCully over the blog.

Through the blog, Mr Carter said he had inside information suggesting the Government was about to back down on a proposal to push for allowing whaling countries to hunt on a limited and diminishing commercial basis.

In an update posted today, Carter accused McCully of having a "temper tantrum" over the blog entry.

"I guess Murray McCully's strong reaction merely confirms that the information I have received from concerned officials is correct and we are going to see yet another flip-flop from the Key Government," he wrote.

IWC member countries are in strained talks about how to find a solution to opposing stances on whaling.

A spokesman from Mr McCully's office told NZPA a briefing planned for today was to keep opposition parties in the loop on whaling talks, but Mr Carter had politicised the situation by attempting to pre-empt the stance of those who were set to give the briefings. He said it was a disruptive stunt which appeared to be seeking to suit his own objectives.

"The minister felt officials were - not surprisingly - upset by accusations Carter has made in his blog, and the minister felt that because it had been politicised we couldn't continue with the briefing we had offered to Labour - which Carter had accepted."

The spokesman dismissed Mr Carter's claims and said proposals would be taken by officials to an IWC support group meeting in Washington starting April 12.

A media briefing on international whaling talks will be held tomorrow by Mr McCully and Sir Geoffrey.

- NZPA