Patient safety will be harmed and victims of medical negligence denied justice because of flaws in the government’s health and care bill, the NHS ombudsman has told the Guardian. Rob Behrens, the parliamentary and health service ombudsman, fears he and his staff will not be able to get to the bottom of clinical blunders because under the bill he will be denied potentially vital information collected by the NHS’s Healthcare Safety Investigation Branch (HSIB). The ombudsman said the legislation would allow the HSIB to “operate behind a curtain of secrecy” and undermine his own investigations into lapses in patient safety and could deny grieving families the full truth about why a loved one died. Behrens has spoken out because he is concerned about government plans for NHS staff involved in an incident to give evidence about mistakes privately in a “safe space” to the HSIB, which cannot be shared with anyone else except coroners. His exclusion from seeing material gathered in that way could force him to take the agency to the high court toaccess it, he said. “If the ‘safe space’ provisions become law as drafted there is a real risk to patient safety and to justice for those who deserve it. This is a crisis of accountability and scrutiny,” he said. The HSIB, set up in 2017 by the then health secretary, Jeremy Hunt, to improve patient safety after the Mid Staffordshire NHS trust scandal, is on course to be put on a legislative footing and renamed the Health Service Safety Investigations Body (HSSIB) in the bill. Both the HSIB and ombudsman publish reports into areas of inadequate NHS care, such as care of people with learning disabilities. “By barring the ombudsman from the information needed to do an effective job the government will be allowing HSSIB to operate behind a curtain of secrecy. It would be a curious anomaly and poor use of taxpayers’ money if two public bodies have to face up in court to get documents handed over,” Behrens said. Julia Neuberger, a crossbench peer who chairs University College hospitals NHS trust, has tabled an amendment to the bill in the House of Lords seeking to give the ombudsman access to information obtained via “safe space” processes. Unless ministers rethink the plan “there could be serious consequences for members of the public who use the ombudsman service”, she recently told a Lords debate. “If the ombudsman is unable to investigate robustly all aspects of complaints about the NHS, except with the permission of the high court, patients may find it harder to get access to justice. The NHS may well become less accountable for its system failings,” she said. Allowing coroners but not the ombudsman access to HSSIB material “does not make sense”, she said. Peter Walsh, chief executive of patient safety charity Action Against Medical Accidents, backed Behrens. “The so-called safe space is a red herring with serious unintended consequences. There is no evidence staff do not take part in investigations for fear of information being known. It is bullying employers and over-zealous regulators that staff fear. Denying people their right to have the ombudsman investigate properly does nothing to address that.” However, Barbara Young, a former chair of the Care Quality Commission, backed the plan and warned that NHS staff would not give evidence to the HSSIB if that information were then shared with the ombudsman. “Any disclosure of protected material to another party represents a risk to the safe space. It would have a chilling effect, preventing people coming forward to HSSIB and therefore making it less able to improve patient safety,” she said. Another peer, Terence Etherton, a leading lawyer and the master of the rolls until last year, is also urging a U-turn. The plan would impede the ombudsman’s work, undermine his independent, non-judicial constitutional role and breach the UK’s obligations as a member of the Council of Europe and UN to support the work of ombudsmen, he said. It was “an incomprehensible inconsistency” to deny the ombudsman information given to coroners, he added. The Lords is due to debate Lady Neuberger’s amendment later this week. The HSIB has been approached for comment.