The scientist at the centre of the climate change data scandal compared himself with David Kelly yesterday, saying that he had contemplated suicide.

Phil Jones expressed regret for attempting to block public access to scientific research, blaming his decision on a campaign by foreign global warming sceptics. He said that the issue was his “David Kelly” moment — a reference to the scientist who killed himself after claims that the Government had “sexed up” a dossier on Iraq’s weapons of mass destruction.

Hackers obtained e-mails that included messages from Professor Jones apparently encouraging climate scientists to refuse Freedom of Information (FOI) requests and even to destroy data, allowing sceptics to claim that scientists were exaggerating the extent of climate change.

Professor Jones, 57, head of the Climatic Research Unit at the University of East Anglia, defended its work but told The Sunday Times that he “misjudged” the handling of requests for information. He said he was provoked into writing the messages after suspecting that his unit was the target of a campaign by climate sceptics to tie up scientists with numerous FOI requests, many from abroad.

He denied that data had been destroyed. “We have no data to delete. It comes to us from around the world. We interpret data. We don’t create or collect it. It’s all available from other sources,” he said.

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.

Yesterday it was reported that the Met Office was refusing to release details of the role of one of its most senior scientists in a report by the United Nations Intergovernmental Panel on Climate Change (IPCC).

John Mitchell, the Met Office’s director of climate science, approved the inclusion of a controversial “hockey stick” graph showing a steep risk in global temperatures in the 20th century.

The Met Office is reported to have blocked the release of the details on the grounds that it “would inhibit the free and frank provision of advice or the free and frank provision of views”.

The report came amid renewed criticism of the IPCC with further claims raising allegations of factual errors and poor sources of evidence.

A leading British Government scientist said that any claims used by the UN climate panel had to be based on hard evidence.

Robert Watson, chief scientist at Defra, the environment ministry, who chaired the IPCC panel from 1997 to 2002, spoke out following doubts about a claim that global warming could cut rain-fed north African crop production by 50 per cent by 2020.

The claim, included in the IPPC’s 2007 report on global warming and repeated in its “Synthesis Report”, has been quoted in speeches by Rajendra Pachauri, the panel’s current chairman, and Ban Ki-moon, the UN Secretary-General.

Professor Watson said: “Any such projection should be based on peer-reviewed literature from computer modelling of how agricultural yields would respond to climate change. I can see no such data supporting the IPCC report.”

Chris Field, the new lead author of the IPCC’s climate impacts team, also said that he could not find support for the statement about African crop yields.

The IPCC claims appears to be traced to an academic paper for a Canadian think-tank that referred to reports by civil servants in Tunisia, Morocco and Algeria, reported The Sunday Times.

There was also criticism yesterday of a diagram in the 2007 report on the potential for generating electricity from wave power, which is reported to have been found to “contain numerous errors”. The Sunday Telegraph also claimed that an unpublished dissertation by a student was used to support a claim that sea-level rise could impact on people living on the Nile delta and other African coastal areas.