Rishi Sunak’s Government has compounded the suffering of victims of the infected blood scandal with the “sluggish pace” and lack of transparency on compensation, an inquiry into the disaster in the NHS has found.

The Prime Minister’s insistence on waiting for the conclusion of the Infected Blood Inquiry before making a final decision on redress has “perpetuated the injustice for victims”, its chairman, Sir Brian Langstaff, said in his final report.

He criticised the “litany of failures” by successive governments from the early 1970s, with no action taken even as it became known that the collection of blood from prisons led to an increased risk of hepatitis transmission.

In recent years, ministers are accused in Sir Brian’s report of “working at a sluggish pace” on the question of compensation.

“People whose lives were torn apart by the wrongs done at individual, collective and systemic levels, and by the way in which successive governments responded to what happened, still have no idea as to the shape, extent or form of any compensation scheme,” Sir Brian wrote.

Mr Sunak, when he was chancellor, failed to respond to two letters from then-paymaster general Penny Mordaunt in 2020 urging the Treasury to begin work on compensation.

In 2021, the Government commissioned a study to provide advice on a potential compensation framework, but did not fulfil its promise to publish its response to the recommendations alongside their release in 2022 – and has still not done so.

This delay means “those infected and affected have felt a lack of transparency and openness characteristic of what they have had to face, and have been fighting, for nearly half a century,” the report said.

Sir Brian also criticised ministers’ insistence on waiting for the report to make final decisions on compensation.

“When the Government knows, as it clearly does, that what happened was a terrible injustice, that people deserve redress, and that lack of redress perpetuates the injustice, then to delay, and thus deny, justice in order to await the ‘full context’ seems hard to justify,” he said.

Given the known urgency, with an estimated one person dying as a result of infected blood every four days, Mr Sunak’s argument that it was “convention” to wait for the conclusion of the inquiry “does not provide a sufficient justification”, the report said.

The report also castigated the historical government response to the emergence of the risks of treating people with contaminated blood and blood products.

Sir Brian took aim at the “institutional defensiveness” in the Civil Service, which he said compounded the failures in decision-making that led to the original infections.

Civil servants persuaded ministers against providing financial support to people infected with hepatitis C throughout the 1990s, with limited money not announced until in 2003, the chairman said.

Measures recommended to end this “defensive culture” include “a statutory duty of accountability on senior civil servants for the candour and completeness of advice” given to top officials and ministers, and in their responses to concerns raised by members of the public.

In the 1980s, the government decided against any form of compensation to people infected with HIV, with Lord Ken Clarke, who was health minister at the time, saying there would be no state scheme to compensate those suffering “the unavoidable adverse effects” of medical procedures.

Then-prime minister Margaret Thatcher rebuffed calls for compensation by asserting in 1989 that people infected with HIV from blood products “had been given the best treatment available on the then current medical advice”.

The repeated use of this mantra by ministers and officials over the next 20 years, including about people infected by other diseases, was “wrong” and “amounted to blindness”, according to Sir Brian.

Sir Brian attacked Lord Clarke’s “combative style” when he gave oral evidence to the inquiry, while campaigners called for an apology from the Tory former minister.

Clive Smith, chair of The Haemophilia Society, said Lord Clarke was “patronising in the extreme” and “had clearly never met anyone with haemophilia”.

“Sadly, he continues in that disposition and I think he owes the community an apology, not just for his time as health secretary but for the manner and the lack of humanity and compassion that he showed when he gave evidence to this inquiry,” he said.

Successive governments also came under fire in the report for their refusal to hold a public inquiry due to “inherent defensiveness”, a reluctance to listen to the stories of ordinary people, and a fear of the expense.

Theresa May finally announced an inquiry in 2017, with the first official hearing held in April 2019.

“I hope that, today, all those infected and affected by the contaminated blood scandal have got the answers they deserve,” Ms May said in response to the report.

“Yet again, a community has had to fight for decades for the truth to come out. We cannot and must not continue to allow a culture whereby institutions seek to protect themselves over the people who have been so damaged by their actions.”

Mr Sunak is expected to issue an apology following the publication of the report on Monday, with ministers preparing to set out the compensation package – thought to be more than £10 billion – on Tuesday.

A Government spokesman said: “This was an appalling tragedy that never should have happened.

“We are clear that justice needs to be done and swiftly, which is why we have acted in amending the Victims and Prisoners Bill.

“This includes establishing a new body to deliver an Infected Blood Compensation Scheme, confirming the Government will make the required regulations for it within three months of Royal Assent, and that it will have all the funding needed to deliver compensation once they have identified the victims and assessed claims.

“In addition, we have included a statutory duty to provide additional interim payments to the estates of deceased infected people.

“We will continue to listen carefully to the community as we address this dreadful scandal.”