UN's climate science body said that the Climategate controversy was the work of a well-thought plan and the hackers were probably paid to do it.

Jean-Pascal van Ypersele, vice-chairman of the Intergovernmental Panel on Climate Change (IPCC), said the theft of emails from the University of East Anglia's Climatic Research Unit (CRU) was not the work of amateur climate skeptics.

Ypersele speculates that hacked emails were done by a well-funded, sophisticated group with the aim of destroying public confidence in the science of man-made climate change.

The fact that the emails were first uploaded to a suspicious website in Russia was an indication that the people behind the controversy were paid, he said.

It's very common for hackers in Russia to be paid for their services.

If you look at that mass of e-mails a lot of work was done, not only to download the data but it's a carefully made selection of e-mails and documents that's not random at all. This is 13 years of data and it's not a job of amateurs.

However, the Climagegate scandal could be used to argue against an international deal to stop global warming at the UN Climate Change Conference in Copenhagen next week.

We are spending a lot of useless time discussing this rather than spending time preparing information for the negotiators, Ypersele said.

Meanwhile, the IPCC chairman, Dr Rajendra Pachauri, said the matter could not be brushed under the carpet.

He has announced a separate investigation by the IPCC, the scientific body charged with reviewing and assessing the latest science on climate change.

We will certainly go into the whole lot and then we will take a position on it, he said.