Infection occurred in the 1970s and 80s
A number of doctors are being investigated after complaints that they broke medical guidelines by testing patients for hepatitis C without their consent.
The inquiry is being carried out by the General Medical Council (GMC).
Haemophiliacs, and other patients, are fighting for a public inquiry after thousands of people were infected by contaminated blood products.
They allege they were secretly tested for the life-threatening virus, and only told they had it years later.
Hepatitis C is classed alongside HIV as a serious communicable disease, and medical guidelines state that doctors must get a patient's consent before testing for it.
During the 1970s and 1980s more than 3,000 haemophiliacs or their families were infected with hepatitis C, which can cause fatal liver problems.
About 500 haemophiliacs were infected north of the border through tainted blood products, along with some 200 other patients.
A Scottish haemophilia action group said that most of its members had been tested for hepatitis C without their permission.
Some of those involved also claim that they were not told the result for four years or more, by which time their families had been put at risk.
I think you have to accept the fact that things were done differently in the past
Dr Charles Saunders
British Medical Association
The GMC is now investigating complaints against several doctors in Scotland and England.
A spokesman said: "We are looking into the
issue of the way patients were treated for blood borne diseases.
"We will look at the complaints and if we have found that there is evidence of professional misconduct we can take it to a final public hearing.
"This can lead to a number of outcomes, including erasure from the register."
Dr Charles Saunders, the chairman of the British Medical Association's public health committee in Scotland, said it was a "very disturbing" story.
But he said: "I think you have to accept the fact that things were done differently in the past.
"Many doctors in the past would have done things that they felt were perhaps in the best interest of their patients."
He said it was "not right" for patients to be tested without consent or to receive results in an insensitive way.
Asked whether such practices had now been eradicated, he said: "I think it's very difficult to say never.
"But one would hope that with the training doctors have received and the different behaviour that patients expect these days that this sort of thing should hopefully be a thing of the past."
Earlier this month the Crown Office in Scotland revealed that it was investigating circumstances around the prescription of contaminated blood.