The UK government's former chief scientist, Sir David King, has claimed that the hacking of climate research emails was planned either by a government agency or by lobbyists hoping to derail the Copenhagen Summit.
King said in an interview with The Independent that the theft is unlikely to be the work of amateur hackers owing to the sophistication of the attack, and that it was most likely to have been carried out by a national government.
"It's the sophistication of the operation. I know there's a possibility that they had a very good hacker working for these people, but it was an extraordinarily sophisticated operation," he said.
"There are several bodies of people who could do this sort of work. These are national intelligence agencies and it seems to me that it was the work of such a group of people."
King added that some of the stolen emails date back to 1996, and that sifting through the vast amounts of data to find the most incriminating emails will have been a huge task.
The release of the information onto a server located in Russia was aimed at disrupting the Copenhagen Summit, and was a well planned and financed operation, according to King.
"If it was a job done on behalf of a government, then I suppose there is the possibility that it could be the Russian intelligence agency," he said.
"If it was a maverick group then I suppose it could be the Americans, but I am hazarding a guess as much as anyone else. I've worked within government and I've seen this in operation.
"In terms of the expense, there is the American lobby system. Right now, the American lobbyists are a very likely source of finance for this, so the finger must point to them."
King's remarks come at a time of increasing disquiet at national governments getting involved in hacking. MI5 claimed yesterday that UK firms are being routinely targeted by Chinese government hackers.
