But the report was immediately branded a "whitewash" by solicitors acting on behalf of the volunteers, who say they are still suffering side effects from the trial drugs.

One man lost the tips of his fingers and toes through a reaction similar to frostbite and doctors fear that another man could develop cancer.

Six men became dangerously ill after being injected with an anti-inflammatory drug TGN1412 in the trials at Northwick Park Hospital, north-west London, in March.

Within minutes they suffered multiple organ failure and their heads and bodies swelled - one patient was described as looking like "the elephant man" after his head swelled.

The drug, developed by the German biotech company TeGenero, was designed to treat rheumatoid arthritis, leukaemia and multiple sclerosis. It was meant to subtly "re-tune" the immune system, but instead sent it into overdrive.

Martyn Day, the solicitor for four of the six victims, said that his clients were "very disappointed" with today's report. "They feel it is simply the latest in a series of whitewashes," he said.

Mr Day said that his clients planned to sue Parexel the research company that conducted the trial.

"What is terribly disappointing about today's report is that it helps my clients not one jot. They are basically left to have the fight with Parexel alone. Depressing as this is for them, my clients are determined to continue, to get justice for what they have been put through," he said.

A drug trial participant, David Oakley, speaking to Sky News said: "We just have to live every day like it's our last because we don't know what's coming up."

Today's report broadly confirms earlier findings from an interim report that was published in July by the same working group of scientists and doctors, led by Professor Gordon Duff.

In future it recommended that "monoclonal antibody" drugs, such as TGN1412, should be initially given to one person at a time and they should be monitored for any adverse reaction. Drugs doses should also be administered over a longer period of time, say up to an hour.

The Medicines and Healthcare products Regulatory Agency (MHRA) has been accused of being too lax in its decision to approve the TGN1412 trial and today's report recommends that in future the body should seek additional advice from independent experts.

The report was drafted after public consultation, including submissions by the pharmaceutical and biotech industries and evidence from four of the volunteers themselves.

Speaking at a news conference today, Professor Duff said: "The alarming outcome of the TGN1412 trial was unprecedented in the history of clinical trials, and we want to record our sympathy for all the trial volunteers. Hearing about their experiences was valuable in making our recommendations, and we are grateful to the volunteers who were able to talk to us.

"There is certainly a need to develop new medicines for conditions where current treatment is inadequate but, in clinical trials the well-being of volunteers must always come first.

"We believe our recommendations would safeguard this in the future."

In a written statement, Andy Burnham, Health Minister, said that an expert advisory group would be set up in the New Year to review applications for trials of high risk substances.

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