The university at the centre of the climate change row over stolen e-mails broke the law by refusing to hand over its raw data for public scrutiny.

The University of East Anglia breached the Freedom of Information Act by refusing to comply with requests for data concerning claims by its scientists that man-made emissions were causing global warming.

The Information Commissioner's Office decided that UEA failed in its duties under the Act but said that it could not prosecute those involved because the complaint was made too late, The Times has learnt. The ICO is now seeking to change the law to allow prosecutions if a complaint is made more than six months after a breach.

The stolen e-mails , revealed on the eve of the Copenhagen summit, showed how the university's Climatic Research Unit attempted to thwart requests for scientific data and other information, and suggest that senior figures at the university were involved in decisions to refuse the requests. It is not known who stole the e-mails.

Professor Phil Jones, the unit's director, stood down while an inquiry took place. The ICO's decision could make it difficult for him to resume his post.

Details of the breach emerged the day after John Beddington, the Chief Scientific Adviser, warned that there was an urgent need for more honesty about the uncertainty of some predictions. His intervention followed admissions from scientists that the rate of glacial melt in the Himalayas had been grossly exaggerated.

In one e-mail, Professor Jones asked a colleague to delete e-mails relating to the 2007 report by the Intergovernmental Panel on Climate Change.

He also told a colleague that he had persuaded the university authorities to ignore information requests under the act from people linked to a website run by climate sceptics.

A spokesman for the ICO said: "The legislation prevents us from taking any action but from looking at the emails it's clear to us a breach has occurred." Breaches of the act are punishable by an unlimited fine.

The complaint to the ICO was made by David Holland, a retired engineer from Northampton. He had been seeking information to support his theory that the unit broke the IPCC's rules to discredit sceptic scientists.

In a statement, Graham Smith, Deputy Commissioner at the ICO, said: "The e-mails which are now public reveal that Mr Holland's requests under the Freedom of Information Act were not dealt with as they should have been under the legislation. Section 77 of the Act makes it an offence for public authorities to act so as to prevent intentionally the disclosure of requested information."

He added: "The ICO is gathering evidence from this and other time-barred cases to support the case for a change in the law. We will be advising the university about the importance of effective records management and their legal obligations in respect of future requests for information."

Mr Holland said: "There is an apparent Catch-22 here. The prosecution has to be initiated within six months but you have to exhaust the university's complaints procedure before the commission will look at your complaint. That process can take longer than six months."

The university said: "The way freedom of information requests have been handled is one of the main areas being explored by Sir Muir Russell's independent review. The findings will be made public and we will act as appropriate on its recommendations."