The NHS has developed a "widespread culture of fear", reports have claimed.
The findings were obtained by centre-right think tank Policy Exchange, with one report accusing the Department of Health of being more interested in costs than clinical quality.
Policy Exchange used the Freedom of Information Act to obtain the documents that had been commissioned by the government.
They were prepared for the Department of Health in 2008 as the government undertook a major restructuring of NHS regulation.
One report, Quality Oversight In England, by the Joint Commission International, identified "the pervasive culture of fear in the NHS and certain elements of the Department of Health".
Another, by the Institute of Healthcare Improvement, said the "NHS has developed a widespread culture more of fear and compliance than of learning, innovation and enthusiastic participation in improvement."
Health experts RAND raised "concerns that the Department of Health is more interested in costs than clinical quality".
Henry Featherstone, from the Health and Social Care Unit at Policy Exchange, said: "Under a proper system of inspection and oversight, coupled with a continual process of performance improvement, hundreds – if not thousands – of lives would be saved."