Former Secretaries of State for Health may be compelled to give evidence to a landmark inquiry into the contaminated blood scandal and be questioned in public for the first time over the disaster.

As the inquiry was officially opened on Monday, its legal counsel said senior politicians would be among those expected to appear before the landmark proceedings.

The Infected Blood Inquiry will investigate how thousands of people in the UK came to contract the HIV and hepatitis C (hep C) viruses through treatment with contaminated blood or blood products.

The deadly treatments were used by the NHS in the 1970s and 1980s and as many as 3,000 people have since lost their lives, while others have lived for decades in debilitating ill health.

Campaigners have long insisted the disaster was avoidable and have made repeated allegations of a cover-up over what happened, but to date no one has been held to account.

As proceedings formally opened on Monday, counsel to the inquiry Jenni Richards QC said she expected former health ministers to be among those who must give evidence.

“We will in the course of the investigative work expect to obtain witness statements from senior politicians, including successive Secretaries of State for Health, from senior civil servants and senior doctors involved in policy-setting and decision-making,” she said.

“We anticipate that a number of such witnesses will be expected to give oral evidence and thus be questioned publicly for the first time about their decisions and actions.

“We expect such witnesses will attend to give evidence without compulsion but the inquiry has no hesitation in using the powers conferred by the Act if so required.”

The inquiry has full statutory status and is established under the 2005 Inquiries Act, giving it full powers to compel the ​production of documents and to summon witnesses to give evidence on oath.

On Sunday, The Sunday Times reported former Prime Minister Sir John Major and former health secretaries Kenneth Clarke, William Waldegrave, Virginia Bottomley, Norman Fowler and John Moore are named in a dossier of people campaigners say have questions to answer over their role in the scandal.

The health ministers served from 1981 to 1992, covering the core years when the disaster was unfolding.

Ms Richards, QC, said: “We would expect to look at the response of government and other bodies, and to examine forensically the issues of a cover-up and lack of candour.”

But she stressed the remit of the inquiry is inquisitorial and not adversarial in nature.

About 500 people were present at Church House in Westminster for the historic  opening today.

Ms Richards revealed that to the best of their knowledge, the inquiry currently has the largest number of core participants of any public probe – with 1,288 already involved, of which 1,272 are affected or infected individuals.

The inquiry’s chairman Sir Brian Langstaff said that the numbers present “paid silent testimony to the sheer scale of the tragedy”.

The former High Court judge explained the purpose of preliminary hearings, held from Monday to Wednesday this week, is to listen to what core participants have to say, and that he is determined the process will be governed by core principles which he laid out.

He said these include keeping people at the heart of the inquiry, that it is properly funded, is as fast as is reasonable, and independent of the government.

Sir Brian also said the inquiry will be UK-wide and will not confine itself to London – with the aim to conduct hearings all over the country including Belfast, Cardiff and potentially Leeds, to enable more affected people to come in person.

With the allegations of a cover-up, which he said will be investigated, Sir Brian stressed that the probe will be as “open and transparent as it is legally possible to be”.

He revealed he is seeking unseen documents, and that the inquiry team already has some material which they would not have had if it was not a statutory inquiry.

“Putting people at the heart of the inquiry must recognise that people have different perspectives to bring to the inquiry,” he said. “It cannot be just a favoured few, or for that matter a favoured many, who are at its heart.

“Those wishing to attribute blame, those who wish neither but just seek to understand why what happened did, or to explain their actions – why they did what they did.

“Those who are haemophiliacs, those who were transfused with infected blood, or those who were both; those who were patients or those who were doctors – all are people, all are entitled to be heard.

“And I would ask all participants to respect that entitlement, however unpalatable they may find some of the ideas or explanations, or accusations or assertions being put forward.”

Following the initial hearings, the inquiry will retire to gather evidence and is expected to reopen on April 30 next year.

Ms Richards QC said no reliable estimate as to how long the inquiry would last could be given, but added it is estimated that once hearings begin they will not take less than a year and a quarter.

Testimonies from those infected and affected by the scandal also featured prominently in a commemoration ceremony that officially opened the inquiry this morning.

In emotional video accounts lasting more than half an hour, people spelled out the life-changing impact and devastating toll on all aspects of their lives as they spoke to the camera.

They described wrecked marriages, lost careers, the agony of having to watch partners and children being tested for viruses they may have passed on, and the stigma of living with HIV and Aids, particularly during the 1970s and 1980s.

Michelle Tolley, who was infected with hep C through a blood transfusions following the birth of her children, said of her diagnosis: “There’s no words to describe that feeling because every time I closed my eyes I was looking at a coffin and I just had that feeling that I was going to die.”

Tony Farrugia, whose haemophiliac father Barry died of Aids aged 37, said: “I was entitled to a family life and I never had that, I grew up in a children’s home, and my father died of a virus that I could never speak about because of the stigma.

“It all needs to be told, the truth needs to come out, sick people shouldn’t have to be fighting for justice. They’ve been put on death row for a crime they didn’t commit.”

Another woman, who was infected with HIV unwittingly by her haemophiliac husband, who died soon after, said: “I want it acknowledged that we were pioneering women. We were the first women to be infected with HIV and how we coped with it and what we did, I want that recognised and accounted for.”

Another man hit out over what had happened, saying: “This is manslaughter. I’m living a slow death never knowing what’s around the corner. This is what the NHS and government did to me and this needs to be corrected. Justice this is what I want.”

People in the film appealed for those responsible to be held accountable and for answers finally to be placed on record about when authorities knew there was a problem with the blood and blood products and what they did afterwards.

They also said every person infected must be found and informed to give them a chance of life. They called for testing for hepatitis C in all standard blood tests to try and identify more of those infected by blood transfusions.

The commemoration service ended as hundreds, many wearing red, filed up to leave messages in bottles in a metal stand at the front of the auditorium as the London Contemporary Voices choir sang the Simon and Garfunkel hit The Sound of Silence.

The inquiry hearing is due to resume on Tuesday and will hear opening statements from core participants in the proceedings.