The writer Nick Hornby today joined autism campaigners in criticising the Shadow Chancellor who appeared to suggest that Gordon Brown could be "faintly autistic".

George Osborne mocked the social skills of his opposite number during a fringe meeting at the Conservative Party Conference in Bournemouth last night, although he has subsequently denied calling Mr Brown autistic.

The comments came as Mr Osborne was talking about his own childhood, saying his brothers had nicknamed him "Knowledge" because he knew so many facts.

The journalist interviewing him at the event organised by the Policy Exchange and IPPR think tanks quipped that he might have been "faintly autistic". Mr Osborne replied: "We’re not getting onto Gordon Brown yet."

Hornby, whose 13-year-old son Danny has autism, said: "George Osborne doesn’t seem to have noticed that most people over the age of eight no longer use serious and distressing disabilities as a way of taunting people."

The author of best-selling novels like Fever Pitch, High Fidelity and About a Boy, helped co-found TreeHouse, an educational charity for children with autism.

He added: "Osborne claims that when he was younger, he was nicknamed ’Knowledge’ - I’m not sure anyone will be calling him ’Knowledge’ again for quite a while."

The National Autistic Society agreed that with Mr Hornby said any perceived use of autism as a term to mock someone could cause "deep distress".

Carol Evans, a director of the charity, said: "Any pejorative use of terms relating to autism can cause deep distress and hurt to people affected by the condition.

"We as a charity are keen to raise awareness in order that these terms are not used lightly by commentators.

"To use such terms as a criticism of someone’s social skills only perpetuates the confusion that surrounds the condition."

The charity said there are an estimated 535,000 people across the UK who are affected by autism.

Mr Osborne later denied suggesting Mr Brown was autistic. His gibe was brought up at a fringe meeting hosted by The Times in Bournemouth, where the Daily Mirror journalist Paul Routledge - who wrote a biography of Gordon Brown - demanded from the floor that he apologise.

Mr Osborne said to delegates: "He's referring to a fringe meeting I was at last night. I think you will find that I didn't use the word autism or autistic at all. Look at the transcript."

Asked if he believed Mr Brown was slightly autistic, Mr Osborne later told Sky News : "No absolutely not. Autism is a very serious condition.

"Do I think that Chancellor Gordon Brown needs better relations with his colleagues, let alone with the opposition front bench? Most certainly."

But in spite of his denial, a source close to Mr Brown told Times Online that Mr Osborne's comments were "deeply offensive" to sufferers and their families and called on him to apologise to them.

"The issue is not about Gordon Brown and whether something is personally offensive to him. It's not something he takes personally.

"However, it is offensive to the thousands of people affected by autism and their families who are seeing the condition used as a form of personal abuse.

"Most people thought we had passed the age when autism was used as a form of playground abuse. That's what's so deeply offensive and he should apologise for it."

The source added: "David Cameron should make clear that it is unacceptable for anyone in the Tory Party to use conditions such as autism as a form of personal abuse."

Labour’s Janet Dean, chairwoman of the All-party Parliamentary Group on Autism and Burton’s MP, echoed the spokesman's concerns.

She said: "I am shocked at the apparent use of the term autism as a method of political abuse. It is offensive and I call on George Osborne to apologise."

The Liberal Democrat chief of staff, Norman Lamb MP, said: "This may have been a casual off-the-cuff remark from George Osborne, but that doesn’t stop it being offensive.

"Opposition politicians have reason enough to criticise the Chancellor without having to descend to these ill-informed comments. This won’t do much to help the attempts to portray the Conservatives as a caring, sharing, modern party."

This is not the first time that a Conservative MP has suggested that Mr Brown is autistic.

Last December Tory backbencher Peter Viggers described the Chancellor as "financially autistic" during a Treasury select committee meeting in the House of Commons.

Mr Brown said at the time that the reference was offensive to people affected by the condition.

The National Autistic Society describes autism as a lifelong developmental disability that affects the way a person communicates and relates to people around them.

Children and adults with autism have difficulties with everyday social interaction, developing friendships and understanding other people's emotions.

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