A Channel 4 documentary that argued that global warning was a fraud is to be criticised by the media regulator.

On Monday Ofcom is expected to publish a long-awaited report that upholds claims by some of the scientists who appeared in the programme last year that they were misrepresented.

The Great Global Warming Swindle, which aired in March last year, has been accused of downplaying the threat in the public mind. It sparked an outcry among environmentalists and many campaigners argue that the programme has contributed to people believing that the threat is not real.

It is understood that complaints by Carl Wunsch, a climate expert at the Massachusetts Institute of Technology, will be upheld. The regulator is expected to say that Channel 4 should have told Dr Wunsch that the programme was going to be a polemic.

The regulator will also uphold complaints made by the government’s former chief scientist, Sir David King, and the Intergovernmental Panel on Climate Change.

But the broadcaster will not be censured over a second complaint about accuracy, which contained 131 specific points and ran to 270 pages, with Ofcom finding that it did not mislead the public.

Debate has raged since the programme was shown, with many scientists claiming that it misrepresented evidence about the threat of global warming and that it rehashed discredited arguments and skewed data and charts to make its arguments stand up. In the closing moments of the program a voiceover from the climate change sceptic Fred Singer claimed that the Chief Scientist of the UK had said that by the end of the century the only habitable place on the planet would be in the Antarctic and that “humanity may survive thanks to some breeding couples who moved to the Antarctic”.

Sir David has never made such a statement. It is thought that Mr Singer confused the comments with those made by the scientist James Lovelock, who infuriated many colleagues in the science community when he publicly questioned global warming.

Ofcom is expected to find that the programme made significant allegations against the Intergovernmental Panel on Climate Change, questioning its credibility and failed to offer it timely and appropriate opportunity to respond.

Channel 4 argues that the organisation refused to cooperate with the programme-makers.

After the broadcast, Dr Wunsch said that the programme was as close to pure propaganda as anything since the Second World War and that he was duped into appearing on it. Martin Durkin, the director of the programme, has defended it vigorously. He wrote in a newspaper: “The death of this theory will be painful and ugly. But it will die. Because it is wrong, wrong, wrong.”

The producers have sold the programme to 21 other countries and a global DVD release went ahead despite protests from scientists.

Channel 4 claimed that the public response to the programme, in the form of phone calls it received, was six to one in favour of it. The broadcaster said that the documentary was a useful contribution to a timely debate, arguing that it had a tradition for iconoclastic programming and that it had also aired programmes supporting the case for man-made climate change.

A recent poll found that the majority of the British public is sceptical that climate change is caused by human activity, with many saying the problem exists but is exaggerated.

Ipsos MORI polled 1,039 adults and found that six out of ten agreed that “many scientific experts still question if human beings are contributing to climate change”. Campaigners believe that steadily increasing economic worries are denting public interest in environmental issues and some of them have blamed the programme.

Channel 4’s head of science, Hamish Mykura, said last March that he commissioned the film because it reflected the views of a significant minority of respected scientists.

An Ofcom spokeswoman said she could not comment before the report was published. Channel 4 said that it could not comment at this stage.

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