Psychiatrists said there was no evidence the treatment worked
Plans to promote medical treatment for homosexuality at a religious conference have been criticised by doctors.
The event will hear from prominent American psychologist Dr Joseph Nicolosi who said he had helped many people to become heterosexual.
But the Royal College of Psychiatrists said there was no supporting evidence and such treatment could be damaging.
The two-day conference being held in central London has been organised by the church group Anglican Mainstream.
'Deal of evidence'
Dr Nicolosi said he had been helping people to "increase their heterosexual potential" for 25 years, and put his success rate among men at about two out of three.
He said he was offering a choice for people who were unhappy being gay.
While the Church of England said it did not promote such therapies, Anglican Mainstream believed such an approach needed to become more well known.
Dr Nicolosi told BBC News: "We have a great deal of evidence showing that these individuals are not harmed and that the therapy does work.
"We are petitioning the American Psychiatric Association to look at the scientific data."
'Prejudice and discrimination'
The Royal College of Psychiatrists (RCP) said there was no evidence that the treatment worked, and that it was likely to cause considerable distress.
An RCP spokesman said: "There is no sound scientific evidence that sexual orientation can be changed.
"Furthermore, so-called treatments of homosexuality create a setting in which prejudice and discrimination can flourish."
The Royal College said the American Psychiatric Association had concluded there was no scientific evidence that homosexuality was a disorder and removed it from its diagnostic glossary of mental disorders in 1973.
The World Health Organisation's International Classification of Diseases followed suit in 1992.
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