New Zealand climate scientists from both sides of the global warming debate have criticised alleged hackers for "stealing" emails at the centre of a worldwide internet storm.

The director of Victoria University's climate change and research institute, Martin Manning, revealed yesterday that emails between him and his son may be in the hands of the hackers, after more than a decade of correspondence between leading climate scientists in Britain, the United States and New Zealand was taken and posted online.

About 1000 emails were published after allegedly being stolen from the University of East Anglia's climate research unit in Britain. The university has not confirmed whether all of the emails are genuine.

It is believed the hackers have released only a selection of what they have, timed to inflict maximum damage on public perceptions of leading climate scientists before a major world conference to address global warming.

In one email, the East Anglia research centre's director, Phil Jones, mentions graphs showing climate statistics over the past millennium and refers to using a technique to "hide the decline" in recent global temperatures.

Niwa principal climate scientist Dr James Renwick said the discussion was "more about how to best present the data than how to fudge something. "There is no cover-up going on.

"When you've got 100MB worth of emails from somebody's personal files, no doubt you can find sentences that taken purely out of context can sound really bad," he said.

But Auckland University scientist Chris de Freitas, whose paper about the influence of El Nino and La Nina on climate was roundly criticised in a series of hacked emails from the middle of this year, said the emails about him showed scientists colluded to make "sweeping attacks" on research they disagreed with - though the remarks made about his paper were no worse than what was said publicly at the time.

"The ganging up on that [paper] is symptomatic of what has been happening for a long time."

He did not agree with the hacking of emails. "I don't for a moment think the ends justified the means."

Dr Renwick said the episode was an "incredible violation of privacy" but he did not believe it would shake the strength of scientific opinion on climate change.

He said it seemed to be an attempt to "muddy the waters" before climate talks in Copenhagen next month.

Dr Martin Manning said private emails between him and his son, Dr Andrew Manning - a research fellow at the University of East Anglia - did not appear to have been posted online, but he was not too concerned as he was usually cautious on email. "I think it is not right for these emails to be distributed like this but I am not too worried about it."

Published emails between him and others relating to the preparation of the most recent IPCC report on climate change were part of a public process.

He said an "enormous amount of the exchange" had been copied to people outside the group of authors at the time, and the resulting report had been publicly and openly reviewed.

He did not think the emails would undermine public confidence in climate science. "I don't think it ever came up about trying to hide things ... I've got two grandchildren - I mean, I would love it if we were wrong [about global warming] ... and I would advertise it as widely as I could."

The Prime Minister's science adviser, Sir Peter Gluckman, has compared climate change sceptics to scientists in the 1980s who disputed that Aids was caused by the HIV virus.

He agreed there were genuine uncertainties in the details of global warming and a remote possibility that if nothing was done the temperature would not rise to unacceptable levels.

"But we cannot gamble the future of the whole planet on the low probability of that occurring," he said in a research paper.

* More than a decade of selected correspondence between leading climate scientists, including about 1000 emails, posted on the internet after allegedly being stolen from the University of East Anglia's climate research unit.
* A few emails appear to show scientists resisting the release of information and attempting to prevent publication of reports expressing countervailing views on climate change.
* Sceptics of man-made global warming say the emails show science underpinning world climate talks is not as certain as leading scientists say.
* Top New Zealand scientists say the body of science underpinning world talks remains strong.