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The Independent Climate Change Email Review was set up by the University of East Anglia after more than 1,000 emails were hacked from its servers.

It found nothing in the emails to undermine Intergovernmental Panel on Climate Change (IPCC) reports.

Accusations that researchers hid key data are largely dismissed.

The review, chaired by former civil servant Sir Muir Russell, has spent months reading submissions sent in by climate scientists and their critics and interviewing key players, notably scientists within the university's Climatic Research Unit (CRU).

On the main charges that climate "sceptics" have levelled against CRU researchers, it concludes that "their rigour and honesty as scientists are not in doubt".

However, it says "there has been a consistent pattern of failing to display the proper degree of openness", notable over complying with Freedom of Information requests.

CRU scientists were too quick to dismiss critics from outside their own circles, it says.

The emails, along with other documents, cover a period dating back to 1997 and were released into the public domain just before the Copenhagen climate summit last year, with some seeing it as a political act designed to destabilise the summit.

CRU produces one of the four most widely used records of global temperature, which have been key to the IPCC's conclusions that the planet's surface is warming and that humanity's greenhouse gas emissions are very likely to be responsible.

Critics have alleged that the unit's scientists withheld temperature data from weather stations and also kept secret the computer algorithms needed to process the data into a record of global temperature.

The review concludes these allegations are unfounded.

"We find that CRU was not in a position to withhold access to such data or tamper with it," it says.

"We demonstrated that any independent researcher can download station data directly from primary sources and undertake their own temperature trend analysis".

Writing computer code to process the data "took less than two days and produced results similar to other independent analyses. No information from CRU was needed to do this".

The inquiry found no evidence that CRU researchers distorted the peer review process employed by scientific journals, or unduly influenced IPCC reports by ignoring research papers that contradicted their own findings.

This the third and most comprehensive review into the CRU issue, and has reached similar conclusions to the previous two.

At the end of March, a report from the House of Commons Science and Technology Committee said the unit should be more open and transparent and must comply with Freedom of Information laws.

And in April, a second inquiry criticised sometimes "messy" practices within the unit and suggested closer liaison with professional statisticians.

But neither found any evidence of malpractice.

Both reviews were criticised in "sceptical" circles as superficial and lacking in balance.

On Monday, a review commissioned by the Dutch government into the IPCC's projections of climate impacts found "no errors that would undermine the main conclusions" - that man-made climate change poses a significant threat in many regions of the world."