A British climate researcher at the centre of a row over global warming science has admitted he wrote some "pretty awful" emails to sceptics when he was refusing their requests for data.

But Phil Jones, of the University of East Anglia's Climatic Research Unit, defended Monday his decision not to release the data about temperatures from around the world, saying it was not "standard practice" to do so.

"I have obviously written some pretty awful emails," Jones told British lawmakers in response to a question about a message he sent to a sceptic in which he refused to release data saying he believed it would be misused.

The admission from the scientist, who has stood aside as director of the climate centre while investigations take place, came at a parliamentary hearing in Britain into the scandal.

The leading research centre came under fire ahead of key climate talks in Copenhagen in December, after more than 1,000 emails and 3,000 other documents were hacked from the university's server and posted online.

Sceptics claimed they showed evidence scientists were manipulating climate data in a bid to exaggerate the case for manmade global warming as world leaders met to try and strike a new accord on climate change.

Jones -- who has said the fallout from the affair prompted him to consider suicide -- had referred in one private email to a "trick" being employed to massage temperature statistics to "hide the decline".

He has since insisted the emails had been taken out of context and labelled allegations that he sought to exaggerate warming evidence as "complete rubbish."

Defending his attempts Monday not to release some of the data requested, Jones said it was publicly available in the United States, adding scientific journals which published his papers had never asked to see it.

The academic also said the unit struggled after being hit by a "deluge" of requests for data last July, made under freedom of information legislation.

Eighty percent of the data used to create a series of average global temperatures showing the world was getting warmer had been released, said the scientist.

Jones also insisted the scientific findings on climate change were robust and verifiable.

The parliamentary hearing is just one of the investigations into the scandal, dubbed "climategate" in the British media, and it looked specifically at the disclosure of data from the unit.

A different independent probe is examining allegations researchers manipulated data, while another will look into the science produced by the unit.