The climate scientists at the centre of a media storm were today cleared of accusations that they fudged their results and silenced critics to bolster the case for man-made global warming.

Sir Muir Russell, the senior civil servant who led a six-month inquiry into the affair, said the "rigour and honesty" of the scientists at the world-leading Climatic Research Unit (CRU) at the University of East Anglia (UEA) are not in doubt. They did not subvert the peer review process to censor criticism as alleged, the panel found, while key data needed to reproduce their findings was freely available to any "competent" researcher.

The panel did criticise the scientists for not being open enough about their work, and said they were "unhelpful and defensive" when responding to legitimate requests made under freedom of information (FOI) laws.

The row was sparked when 13 years of emails from CRU scientists were hacked and released online last year. Climate change sceptics claimed they showed scientists manipulating and suppressing data to back up a theory of man-made climate change. Critics also alleged that the scientists abused their positions to cover up flaws and distort the peer review process that determines which studies are published in journals, and so enter the scientific record. Some alleged that the emails cast doubt on the findings of the Intergovernmental Panel on Climate Change (IPCC).

Announcing the findings, Russell said: "Ultimately this has to be about what they did, not what they said."

He added: "The honesty and rigour of CRU as scientists are not in doubt ... We have not found any evidence of behaviour that might undermine the conclusions of the IPCC assessments."

The review is the third and final inquiry into the email affair, dubbed "climategate", and effectively clears Professor Phil Jones, head of the CRU, and his colleagues of the most serious charges. Questions remain over the way in which they responded to requests for information from people outside the conventional scientific arena, some of whom were long-standing critics of Jones.

"We do find that there has been a consistent pattern of failing to display the proper degree of openness, both on the part of CRU scientists and on the part of the UEA," the report, commissioned by UEA, said.

It also criticised the CRU scientists for failing to include proper labels on a 1999 graph prepared for the World Meteorological Organisation, which was the subject of an infamous email about Jones using a "trick" to "hide the decline". The panel said the result was misleading, though they accepted this was not deliberate as the necessary caveats had been included in the report text.

Separately, it was announced today that Phil Jones has accepted the new post of director of research at CRU. The vice chancellor of UEA, Professor Edward Acton, said this was "not a demotion but a shift in emphasis of role" for Phil Jones. "CRU will be more closely integrated in the bigger school of environmental sciences and a key difference is to place some of the administrative burden that Phil had before this incident on the head of the school," said Prof Acton. Jones will be more free to direct and conduct his own research.

Future FOI requests for the CRU will be directed though the head of the school, Professor Jacquie Burgess, and the ultimate responsibility for such requests will lie with the vice-chancellor, as highlighted in the Russell report.

• Additional reporting by Christine Ottery