Mrs Daly said yesterday that the email, made public by computer hackers, had only made her more determined to spread her late husband's message.

It was written by the head of Britain's Climatic Research Unit Phil Jones, who wrote to a colleague that the death of John Daly was "cheering news".

The news made the front page of a national newspaper this week, which reported the email - titled "John L. Daly dead" - was sent just after Mr Daly's death in 2004 with his death notice attached.

A regular letter writer to The Examiner, Mr Daly died of a heart attack at his Hadspen home.

Through tears, Mrs Daly said yesterday that the email had brought back distressing memories of the day she tried unsuccessfully to resuscitate her husband of 35 years.

"It's such a cowardly thing to do," Mrs Daly said of the email.

"John never ever did anything like that - he stuck to the scientific things, he stuck to the debate."

Mrs Daly said her grandson told her about the email, which had devastated her whole family.

"It's a big blow to him, it's a big blow to my daughters," she said.

She said she would not try to contact Professor Jones.

"If he says such things about John then obviously he had a fear of John - he thought he didn't have enough scientific knowledge to challenge it so he had to do something as nasty as that."

The Guardian newspaper reported that Professor Jones refused to comment on whether the leaked emails were genuine.

The climate had been a lifelong passion for Mr Daly, who first started to study the topics as an officer in the Merchant Navy, Mrs Daly said.

He believed that global warming was a scare campaign.

As well as maintaining a website, Mr Daly was the author of a book and numerous articles about the contentious issue.

Professor Jones and Mr Daly met in 2001, when the scientist demanded the then-58-year-old remove an article from his website that questioned the quality of his research.

Mr Daly refused, simply answering "no".

The email exchange between the two men is still posted on Mr Daly's website - www.john-daly.com.

Mrs Daly vowed to maintain her late husband's website, saying it was important to maintain debate.

"The last thing I want is to lose all the work John did," she said.

"He spent 15 years doing it.

"Also, it's important that climate change should be proved."