A self-styled "reverend" who claims autism can be "purged" by swallowing bleach has been exposed by a BBC London undercover investigation.
Leon Edwards sold sodium chlorite and hydrochloric acid to a reporter posing as the relation of an autistic child. Combined, the chemicals form bleach.
The BBC has also learned the secret location of a conference to begin in Surrey on Friday to promote the 'cure'.
When confronted with the evidence, Mr Edwards made no comment.
Mr Edwards has been linked to the Genesis II Church, an American organisation which describes itself as a "non-religious church of health and healing".
This is purportedly achieved through the used of so-called "Miracle Mineral Solution" (MMS), a bleach which is produced by mixing the two chemicals.
Experts said it is untrue any such mixture could cure autism and warned its use could lead to serious harm or death.
Some of the leading figures in the 'church' have travelled from the US to attend the conference, due to take place in a manor house in Farnham.
Emails obtained by the BBC show delegates have been told to meet at a certain location before being driven to the venue, where they will be instructed in preparing doses of MMS to be consumed orally and taken via enemas.
Through his website, Mr Edwards, who says he is not attending the conference, sold the researcher the one bottle of liquid labelled as 22.4% sodium chlorite and a second labelled as 4% hydrochloric acid.
When the BBC sent the chemicals to Kent Scientific Services, an independent laboratory, they were found to be 57% and 45% stronger than the advertised concentration respectively.
The researcher then met Mr Edwards at King's Cross Station for a paid-for demonstration as to how they should be mixed and imbibed.
Mr Edwards told him: "It's helping people get well from all sorts of diseases - cancer, HIV, malaria. It's cleaning the body out. And nearly all the illnesses are getting removed with this.
"I'm not gonna say cure... because I can get in trouble. I'd say purge. It can purge autism. Alzheimer's too.
"170 children have had their diagnosis removed of autism in four years."
Mr Edwards advised 27 drops of MMS per day for a baby - administered with a baby's bottle.
Of his own use, he said: "I put it in my eyes, my nose, my ears, bathe in it, drunk it, breathed it in my lungs. I got injected in my butt with it.
"They're never gonna shut me down. All they can do is put me in a prison cell."
Last month a jury in the US state of Washington convicted Genesis II member Louis Daniel Smith for selling MMS as a "miracle cure". He faces a maximum of 34 years in prison.
Carol Povey, of the National Autistic Society, said: "No evidence of any kind exists to support the preposterous claims made for MMS as an intervention for autism.
"It is shocking that dubious companies continue to promote potentially very harmful products like these.
"Autism is a complex neurological condition, without a cure."
Dr Sarah Jarvis, a GP, said ingesting bleach could cause scarring to the oesophagus, damage to the stomach and even death.
She explained: "A very small amount of concentrated bleach has the possibility of doing great harm.
"This is particularly true of a child's gut lining, which is thinner than an adults.
"It is an extra danger that people are self-administering this as the dose could easily be got wrong."
Prof Richard Goldberg, expert in pharmaceutical law at Durham Law School, warned selling sodium chlorite for consumption breached the Food Supplements England Regulations.
"This is a potential criminal offence," he said. "The Food Standards Agency has to inform the relevant local authority and the authority has to take action.
"There is a very strong argument that he is selling an unauthorised food supplement. There is a potential argument for him selling an unauthorised medicine."
An organiser of the Genesis II Church conference described MMS as a "sacrament" that was "no different than the bread and wine given during a church service".
The spokeswoman continued: "The so-called side effects are far less than [in] drugs sold by pharmaceutical companies.
"We are not selling any products during the church services. We simply conduct our services and share our news and protocols.
"Table salt is dangerous if taken too much [sic]."
Surrey County Council says it will try to disrupt the conference and warned the public against trying MMS.
Fiona O'Leary, a mother of two autistic children, is a leading campaigner against MMS. She warned: "This has been offered as a cure for autism in 60 countries.
"What worries me is people normalising this treatment - it does not even warrant the word treatment, autism is not a 'disease' that you can 'cure' with bleach.
"We need legislation so that people offering it are always prosecuted, but we don't see the authorities addressing this issue."
She added: "The suffering children are going through is shocking - it's child abuse."