A doctor who exploited a group of "vulnerable" multiple sclerosis patients used stem cells that were not designed for human use, a fitness to practise panel found.
Nine men and women, most of whom were suffering from "incurable conditions", visited Dr Robert Trossel, "desperate" to find some relief for their disease and prepared to raise large sums of money to fund their therapy.
But the General Medical Council panel found Dr Trossel, 55, exaggerated the benefits of treatment which was based on "anecdotal and aspirational information" and "scientific research that had been carried out only on animals".
The Dutch-trained doctor also lacked the necessary knowledge to embark on the therapy, the panel said, while overstating his success rate at treating people with multiple sclerosis - a disabling neurological disease.
"The panel is satisfied that there was neither sufficient scientific nor clinical medical evidence upon which to proceed with the stem cell therapy," it said in a report into the findings of facts.
"Further, Dr Trossel did not have the necessary neurological or scientific expertise upon which to proceed with such therapy," the panel concluded.
And it said Dr Trossel "was not in a position" to supply adequate information to ensure patients could give informed consent to treatment.
He also failed to respect the rights of the patients to be fully involved in decisions about their care when they visited him in his clinic in Rotterdam, it said.
At an earlier hearing, Dr Trossel said he only discovered a batch of vials sent to him in 2006 by Advanced Cell Therapeutics (ACT) were not designed for human use when he took part in a BBC Newsnight programme.
A sticker providing information about where the vials came from was later brought to his attention.
Dr Trossel said he looked into California-based All Cells - named on the sticker - and found a disclaimer stating it only produced materials for laboratory use.
He contacted All Cells and failed to get confirmation the cells could be used on humans, telling the hearing: "We couldn't get the confirmation so we immediately stopped all treatments with ACT patients".
The doctor said he was told the consignment had been sent in error and was provided by All Cells for research.
From that point, he said patients were only treated with cells bought from a supplier in Pakistan which provided necessary certification for human use.
Besides his Preventief Medisch Centrum clinic in Rotterdam, Dr Trossel had consulting rooms in New Cavendish Street and Wimpole Street, London.
In October 2006, he was ordered by the Dutch authorities to cease stem cell treatment, the GMC heard.
ACT's bosses, Laura Brown and Steve van Rooyen, underwent investigation by US authorities and were facing extradition proceedings from South Africa, the panel heard.
The nine patients involved in the case against Dr Trossel are James McCorrisken, Malcolm Pear, Stephen Murphy, Anita Knowles, Rebecca Parker, Catherine Neal, Tracy Wagstaff, Karen Galley and Deborah Sandford.
Dr Trossel denied a series of charges relating to the patients including acting in a way that was inappropriate and exploitative of vulnerable patients.
In a tenth case, Dr Trossel denied making false and misleading statements to investigative journalist Barney Calman, who visited his private clinic in London claiming to have Hodgkin's disease in 2006.
Tom Kark, counsel for the GMC, previously said that in the majority of cases, the treatment administered by Dr Trossel had "no effect" and there was "no evidence" the substance injected contained stem cells.
The panel also heard that the Saudi Arabia-born doctor's fitness to practise was impaired because of a conviction in Antwerp in February last year over stem cell treatment offences under Belgian law.
He received a police caution in 2007 for failing to pay a car park charge at Stansted airport, the panel was told.
It will resume consideration of Dr Trossel's case on September 6 when it will hear submissions as to whether his fitness to practise is impaired.