A number of researchers working on Chronic Fatigue Syndrome or ME have been directly targeted in a campaign of abuse and intimidation by those angry at any association of the condition with mental illness.

As Tom Feilden reports, leading scientists have voiced concern that the "torrent of abuse" is preventing scientists from going into the field.

Dr Charles Shepherd, medical adviser to the ME Association, said that personal intimidation was both "unacceptable" and "counter-productive".

"It puts good researchers off, there's no doubt about that," he told Sarah Montague.

But putting the anger "into context", Dr Shepherd explained how the medical profession had re-defined the illness to include a "wider spectrum" of conditions and triggers.

"There may be a psychological input to the illness in some people... but the anger, the frustration, is the fact that all this government funding has just been going to [researching] the psychological side."

He added that until different sub-groups had been explored properly, a cure could not be found.

"I don't want to see scientists leaving the field, I want a debate with scientists... it should be conducted through the medical journals, it should be conducted through constructive criticism. Intimidation and personal abuse has no role to play in this whatsoever."

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