The United Nations panel of climate science, headed by Rajendra Pachauri, faces new controversy for wrongly linking global warming to a rise in natural disasters such as hurricanes and floods.
According to The Sunday Times, the panel based the claims on an unpublished report that had not been subjected to routine scientific scrutiny - and ignored warnings from scientific advisers. The report's author later withdrew the claim because the evidence was too weak.
The link was central to demands at last month's Copenhagen climate summit by African nations for compensation of $100 billion from the rich nations blamed for creating the most emissions.
According to the newspaper, the panel knew in 2008 that the link could not be proved but did not alert world leaders.
Ed Miliband, the energy and climate change minister, has suggested British and overseas floods - such as those in Bangladesh in 2007 - could be linked to global warming.
US President Barack Obama said last autumn: "More powerful storms and floods threaten every continent."
In another report, The Sunday Telegraph said the scientist whose report originally claimed that Himalayan glaciers could disappear by 2035, has for the past two years been working as a senior employee of The Energy and Resources
Institute, (TERI) the Delhi-based company of which Dr Pachauri is director-general.