British authorities and the country’s public health service knowingly exposed tens of thousands of patients to deadly infections through contaminated blood and blood products, and hid the truth about the disaster for decades, an inquiry into the U.K.’s infected blood scandal found Monday.

An estimated 3,000 people in the United Kingdom are believed to have died and many others were left with lifelong illnesses after receiving blood or blood products tainted with HIV or hepatitis in the 1970s to the early 1990s.

The scandal is widely seen as the deadliest disaster in the history of Britain’s state-run National Health Service since its inception in 1948.

Former judge Brian Langstaff, who chaired the inquiry, slammed successive governments and medical professionals for “a catalogue of failures” and refusal to admit responsibility to save face and expense. He found that deliberate attempts were made to conceal the scandal, and there was evidence of government officials destroying documents.

“This disaster was not an accident. The infections happened because those in authority — doctors, the blood services and successive governments — did not put patient safety first,” he said. “The response of those in authority served to compound people’s suffering.”

Prime Minister Rishi Sunak apologised to the victims and said the report’s publication marked “a day of shame for the British state.”

Campaigners have fought for decades to bring official failings to light and secure government compensation. The inquiry was finally approved in 2017, and over the past four years it reviewed evidence from more than 5,000 witnesses and more than 100,000 documents.