Six volunteers who were taken seriously ill during a drugs trial have been offered an interim payment of £5,000, if they agree not to sue.
The men suffered multiple organ failure
Lawyers for four of the men said the drug manufacturer, TeGenero, had agreed to pay compensation but had attached a "no-fault" clause in the agreement.
The four men have turned down the company's offer, but TeGenero said the claims are still being processed.
The trial was at Northwick Park Hospital, north-west London, in March.
The four men's lawyer, Martyn Day, said it was inappropriate to try to force his clients' hands.
He said his clients had instructed him not to accept the offer.
"They were very cross. They feel they have lost a lot and the burden of the trials hangs very much with them," he said.
"We had asked for a £10,000 interim payment as it seemed a sensible figure to tide them over until this was resolved.
"I was surprised to find that they had halved the figure and tied this into asking our clients to sign up to this compensation scheme."
He said although this may turn out to be the appropriate route it was too early for his clients to make a decision.
"They have put these clients through such anguish, it is totally inappropriate to try to force their hand," he said.
The previously healthy men had been given the TGN1412 drug by medical research company Parexel.
They had volunteered to test the medication, which was designed to treat rheumatoid arthritis, leukaemia and multiple sclerosis.
Mr Day said the crucial question was to determine what problems they would face in the future before any such decision was taken.
"In the next few weeks we will be looking at assessing quite how serious their situation is and once that's clear things will start to fall into place," he said.
This week it emerged the drug's manufacturers had only £2m insurance for the trial.
A spokesman for TeGenero said: "We are keen that the volunteers receive appropriate compensation as soon as possible.
"The claims are currently being processed by our insurers and we understand that this offer of interim payment does not eliminate the possibility of the volunteers pursuing a route other than the no-fault arrangement detailed in the original volunteer consent form."