Survivors of the contaminated blood scandal and their families are refusing to meet with Government officials ahead of an official of an official inquiry into how they were left exposed to disease.
Members of several groups have said they will boycott a planned meeting with the Department of Health (DH) which is intended to help set the terms of the review.
They have said it is inappropriate for the department to be involved when it is itself under investigation over alleged failures to protect patients who were given blood products infected with hepatitis C and HIV.
Around 2,400 were killed after being infected with serious illnesses from transfusions given in the 1970s and 80s, with documents suggesting that health chiefs were aware of the risks.
A joint statement from groups including Tainted Blood, the Forgotten Few, Positive Women and the Contaminated Blood Campaign said they "universally reject" the planned meeting with the DH today.
"We do not believe that the DH should be allowed to direct or have any involvement into an investigation into themselves, other than giving evidence.
The handling of this inquiry must be immediately transferred elsewhere."
– JOINT STATEMENT
Liz Carroll, the chief executive of the Haemophilia Society, also turned down an invite to the meeting.
In a letter to Theresa May, she said that campaigners and MPs alike argued that the department "must not be involved in deciding the remit and powers of an inquiry that will be investigating the actions of its ministers and staff".
"I am sure you can imagine the distress and distrust this would cause for those who are so desperate for the truth to be told."
She called for the managing of the inquiry to be passed to another department and the meeting with Government health officials to be cancelled.
The meeting is still believed to be going ahead despite the outcry.
A Department of Health spokeswoman said: "We are absolutely committed to a thorough and transparent inquiry.
"To establish the best format and remit, we want to hear as many opinions as possible. Our door is open for anyone who wants to discuss the inquiry or raise any concerns."
Downing Street insisted the inquiry would be independent and concerned parties would be asked whether they wanted a judge-led inquiry or a Hillsborough-style panel.